JPH11161939A - Substrate for magnetic recording medium having nonmagnetic ground surface layer and magnetic recording medium using this substrate - Google Patents

Substrate for magnetic recording medium having nonmagnetic ground surface layer and magnetic recording medium using this substrate

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Publication number
JPH11161939A
JPH11161939A JP34383497A JP34383497A JPH11161939A JP H11161939 A JPH11161939 A JP H11161939A JP 34383497 A JP34383497 A JP 34383497A JP 34383497 A JP34383497 A JP 34383497A JP H11161939 A JPH11161939 A JP H11161939A
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JP
Japan
Prior art keywords
magnetic
particles
magnetic recording
recording medium
nonmagnetic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP34383497A
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Japanese (ja)
Other versions
JP3661738B2 (en
Inventor
Kazuyuki Hayashi
一之 林
Keisuke Iwasaki
敬介 岩崎
Hiroko Morii
弘子 森井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toda Kogyo Corp
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Toda Kogyo Corp
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Publication date
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Priority to JP34383497A priority Critical patent/JP3661738B2/en
Priority to US09/198,390 priority patent/US6159592A/en
Priority to EP98309710A priority patent/EP0923068A3/en
Publication of JPH11161939A publication Critical patent/JPH11161939A/en
Application granted granted Critical
Publication of JP3661738B2 publication Critical patent/JP3661738B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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  • Compounds Of Iron (AREA)
  • Magnetic Record Carriers (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having a low light transmittance, surface smoothness, high strength and excellent durability. SOLUTION: The nonmagnetic particle powder of the substrate for the magnetic recording medium consisting of a nonmagnetic base and a nonmagnetic ground surface layer which is formed on this nonmagnetic base and contains nonmagnetic particle powder and a binder resin is the acicular nonmagnetic particle powder consisting essentially of iron contg. zirconium of 0.05 to 30 wt.% in terms of Zr within the particles. The substrate for the magnetic recording medium having the nonmagnetic ground surface layer using such nonmagnetic particle powder and the magnetic recording medium using such substrate are thus obtd.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は、光透過率が小さく、表
面平滑で、強度が大きく、且つ、耐久性に優れた非磁性
下地層を有する磁気記録媒体用基体及び該基体を用いた
磁気記録媒体を提供することを目的とする。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a magnetic recording medium having a nonmagnetic underlayer having a low light transmittance, a smooth surface, a high strength and an excellent durability, and a magnetic material using the substrate. It is intended to provide a recording medium.

【０００２】[0002]

【従来の技術】近年、ビデオ用、オーディオ用磁気記録
再生用機器の長時間記録化、小型軽量化が進むにつれ
て、磁気テープ、磁気ディスク等の磁気記録媒体に対す
る高性能化、即ち、高密度記録化、高出力特性、殊に周
波数特性の向上、低ノイズ化の要求が益々強まってい
る。2. Description of the Related Art In recent years, as long-term recording and miniaturization of video and audio magnetic recording / reproducing devices have progressed, the performance of magnetic recording media such as magnetic tapes and magnetic disks has been improved. There is an increasing demand for higher performance, higher output characteristics, especially improved frequency characteristics, and lower noise.

【０００３】磁気記録媒体のこれら諸特性を向上させる
ために、磁性粒子粉末の高性能化及び磁気記録層の薄層
化の両面から、種々の試みがなされている。Various attempts have been made to improve these various properties of the magnetic recording medium, from both aspects of improving the performance of the magnetic particle powder and reducing the thickness of the magnetic recording layer.

【０００４】先ず、磁性粒子粉末の高性能化について述
べる。[0004] First, the performance improvement of magnetic particle powder will be described.

【０００５】磁気記録媒体に対する上記のような要求を
満足させる為に適した磁性粒子粉末の特性は、高い保磁
力と大きな飽和磁化とを有することである。[0005] The characteristics of the magnetic particle powder suitable for satisfying the above requirements for the magnetic recording medium are to have a high coercive force and a large saturation magnetization.

【０００６】近年、高出力並びに高密度記録に適する磁
性粒子粉末として針状マグヘマイト粒子や針状マグネタ
イト粒子にＣｏを被着したＣｏ被着型磁性酸化鉄粒子や
針状ゲータイト粒子又は針状ヘマタイト粒子を還元性ガ
ス中で加熱還元することにより得られる鉄を主成分とす
る針状金属磁性粒子粉末が広く使用されている。In recent years, as magnetic particle powder suitable for high-output and high-density recording, acicular maghemite particles, Co-coated magnetic iron oxide particles in which Co is applied to acicular magnetite particles, acicular goethite particles, or acicular hematite particles. Needle-like metal magnetic particle powder containing iron as a main component obtained by heating and reducing in a reducing gas is widely used.

【０００７】次に、磁気記録層の薄層化について述べ
る。Next, the thickness reduction of the magnetic recording layer will be described.

【０００８】近時におけるビデオテープの高画像高画質
化に対する要求は益々強まっており、従来のビデオテー
プに比べ、記録されるキャリアー信号の周波数が益々高
くなっている。即ち、短波長領域に移行しており、その
結果、磁気テープの表面からの磁化深度が著しく浅くな
っている。In recent years, the demand for higher image quality and higher image quality of video tapes has been increasing more and more, and the frequency of a carrier signal to be recorded is higher than that of conventional video tapes. That is, the wavelength shifts to the short wavelength region, and as a result, the magnetization depth from the surface of the magnetic tape becomes extremely shallow.

【０００９】短波長信号に対して、磁気記録媒体の高出
力特性、殊に、Ｓ／Ｎ比を向上させる為には、磁気記録
層の薄層化が強く要求されている。この事実は、例え
ば、株式会社総合技術センター発行「磁性材料の開発と
磁粉の高分散化技術」（１９８２年）第３１２頁の「‥
‥塗布型テープにおける高密度記録のための条件は、短
波長信号に対して、低ノイズで高出力特性を保持できる
ことであるが、その為には保磁力Ｈｃと残留磁化Ｂｒが
‥‥共に大きいことと塗布膜の厚みがより薄いことが必
要である。‥‥」なる記載の通りである。In order to improve the high output characteristics of a magnetic recording medium, especially the S / N ratio, for a short wavelength signal, it is strongly required to make the magnetic recording layer thinner. This fact is described in, for example, “‥ Development of Magnetic Materials and Technology for Highly Dispersing Magnetic Powder” published by Sogo Gijutsu Center (1982), p.
The condition for high-density recording in a coating type tape is to be able to maintain high output characteristics with low noise for a short wavelength signal. For this purpose, both the coercive force Hc and the residual magnetization Br are large. And the thickness of the coating film must be thinner. ‥‥ ”.

【００１０】磁気記録層の薄層化が進む中で、いくつか
の問題が生じている。第一に、磁気記録層の平滑化と厚
みむらの問題であり、周知の通り、磁気記録層を平滑で
厚みむらがないものとするためには、ベースフィルムの
表面もまた平滑でなければならない。この事実は、例え
ば、工学情報センター出版部発行「磁気テープ−ヘッド
走行系の摩擦摩耗発生要因とトラブル対策−総合技術資
料集（−以下、総合技術資料集という−）」（昭和６２
年）第１８０及び１８１頁の「‥‥硬化後の磁性層表面
粗さは、ベースの表面粗さ（バック面粗さ）に強く依存
し両者はほぼ比例関係にあり、‥‥磁性層はベースの上
に塗布されているからベースの表面を平滑にすればする
ほど均一で大きなヘッド出力が得られＳ／Ｎが向上す
る。‥‥」なる記載の通りである。As the thickness of the magnetic recording layer has been reduced, several problems have arisen. First, there is a problem of smoothing and uneven thickness of the magnetic recording layer. As is well known, in order to make the magnetic recording layer smooth and free of thickness unevenness, the surface of the base film must also be smooth. . This fact can be found, for example, in “Implementation of Engineering Information Center,“ Magnetic Tape-Factor / Wear Occurrence Factors and Trouble Measures for Head Running System-Comprehensive Technical Data Collection (hereinafter referred to as “Comprehensive Technical Data Collection-”) ”(Showa 62)
Years) p. 180 and p. 181 "The surface roughness of the magnetic layer after hardening strongly depends on the surface roughness (back surface roughness) of the base, and both are almost proportional to each other. As the surface of the base is made smoother, a uniform and large head output is obtained and the S / N is improved.

【００１１】第二に、ベースフィルムもまた磁性層と同
様に薄層化が進んでおり、その結果、ベースフィルムの
強度が問題となってきている。この事実は、例えば、前
出「磁性材料の開発と磁粉の高分散化技術」第７７頁の
「‥‥高密度記録化が今の磁気テープに課せられた大き
なテーマであるが、このことは、テープの長さを短くし
てカセットを小型化していく上でも、また長時間記録に
対しても重要となってくる。このためにはフィルムベー
スの厚さを減らすことが必要な訳である。‥‥このよう
に薄くなるにつれてテープのスティフネスが急激に減少
してしまうためレコーダーでのスムーズな走行がむずか
しくなる。ビデオテープの薄型化にともない長手方向、
幅方向両方向に渡ってのこのスティフネスの向上が大い
に望まれている。‥‥」なる記載の通りである。Second, the thickness of the base film has also been reduced as in the case of the magnetic layer, and as a result, the strength of the base film has become a problem. This fact is described, for example, in the above-mentioned “Development of Magnetic Materials and Technology for Highly Dispersing Magnetic Particles” on page 77, “‥‥ High Density Recording is a major theme that has been imposed on current magnetic tapes. This is important in reducing the length of the tape to reduce the size of the cassette and for long-time recording, which requires reducing the thickness of the film base. The stiffness of the tape suddenly decreases as the thickness decreases, making it difficult for the recorder to run smoothly.
It is greatly desired to improve the stiffness in both width directions. ‥‥ ”.

【００１２】ところで、現在、特にビデオテープ等の磁
気記録媒体の磁気テープ終端の判定は、磁気記録媒体の
光透過率の大きい部分をビデオデッキによって検知する
ことにより行われている。磁気記録媒体の薄層化や磁気
記録層中に分散されている磁性粒子粉末の超微粒子化に
伴って磁気記録層全体の光透過率が大きくなるとビデオ
デッキによる検知が困難となる為、磁気記録層にカーボ
ンブラック等を添加して光透過率を小さくすることが行
われている。そのため、現行のビデオテープにおいては
磁気記録層へのカーボンブラック等の添加は必須となっ
ている。By the way, at present, the determination of the end of a magnetic tape of a magnetic recording medium such as a video tape is performed by detecting a portion of the magnetic recording medium having a high light transmittance by a video deck. As the light transmittance of the entire magnetic recording layer increases as the thickness of the magnetic recording medium becomes thinner and the magnetic particles dispersed in the magnetic recording layer become ultrafine, the detection by the video deck becomes difficult. The light transmittance is reduced by adding carbon black or the like to the layer. Therefore, in current video tapes, the addition of carbon black or the like to the magnetic recording layer is indispensable.

【００１３】しかし、非磁性のカーボンブラック等を多
量に添加することは、高密度記録化を阻害するばかりで
なく、薄層化をも阻害する原因となる。磁気テープの表
面からの磁化深度を浅くして、磁気テープの薄層化をよ
り進めるためには、磁気記録層に添加するカーボンブラ
ック等の非磁性粒子粉末をできるだけ少なくすることが
強く要求されている。However, adding a large amount of non-magnetic carbon black or the like not only hinders high-density recording, but also hinders thinning. In order to make the magnetization depth from the surface of the magnetic tape shallower and to further reduce the thickness of the magnetic tape, it is strongly required to reduce the amount of non-magnetic particles such as carbon black added to the magnetic recording layer as much as possible. I have.

【００１４】そこで、磁気記録層に添加するカーボンブ
ラック量を少なくしても光透過率が小さい磁気記録媒体
が強く要求されており、この点からも基体の改良が強く
要求されている。Therefore, there is a strong demand for a magnetic recording medium having a small light transmittance even if the amount of carbon black added to the magnetic recording layer is reduced, and from this point, there is also a strong demand for improvement of the substrate.

【００１５】更に、近時における磁気記録媒体の高性能
化の要求はとどまるところがなく、上述した磁気記録層
の薄層化や非磁性支持体の薄層化に伴って、磁気記録層
表面や磁気記録媒体自体の耐久性が低下することとなる
ため、磁気記録層表面や磁気記録媒体自体の耐久性を向
上させることが強く要求されている。Furthermore, there is no limit to the recent demand for higher performance of magnetic recording media, and with the aforementioned thinner magnetic recording layer and thinner non-magnetic support, the surface of magnetic recording layer and magnetic Since the durability of the recording medium itself decreases, there is a strong demand for improving the durability of the magnetic recording layer surface and the durability of the magnetic recording medium itself.

【００１６】この事実は、特開平５−２９８６７９号公
報の「‥‥近年、磁気記録の発展と共に高画質、高音質
の要求がますます高まっており、電磁変換特性の改良、
特に強磁性粉末の微粒子化、高密度化が進められ、更に
磁気テープの表面を平滑化することでノイズを下げ、Ｃ
／Ｎを上げることが要求されている。‥‥しかしなが
ら、磁気テープの走行中において磁性層と装置系との接
触の摩擦係数が増大する結果、短時間の使用で磁気記録
媒体の磁性層が損傷を受け、あるいは磁性層が剥離する
傾向がある。特にビデオテープではビデオヘッドと磁気
記録媒体が高速で接触しながら走行するため、磁性層か
ら強磁性粉末が脱落しやすく、磁気ヘッドの目詰まりの
原因ともなる。従って、磁気記録媒体の磁性層の走行耐
久性の向上が望まれている。‥‥」なる記載から明らか
である。This fact is described in Japanese Unexamined Patent Publication No. Hei 5-298679, "‥‥ Recently, with the development of magnetic recording, the demand for high image quality and high sound quality has been increasing more and more.
In particular, the ferromagnetic powder has been reduced in particle size and density, and the noise has been reduced by smoothing the surface of the magnetic tape.
/ N is required to be increased. However, as the friction coefficient of the contact between the magnetic layer and the device system increases during the running of the magnetic tape, the magnetic layer of the magnetic recording medium is likely to be damaged or the magnetic layer to be peeled off in a short time use. is there. Particularly, in the case of a video tape, since the video head and the magnetic recording medium run while contacting each other at a high speed, the ferromagnetic powder tends to fall off the magnetic layer, which causes clogging of the magnetic head. Therefore, it is desired to improve the running durability of the magnetic layer of the magnetic recording medium. It is clear from the description “‥‥”.

【００１７】磁気記録層の薄層化や非磁性支持体の薄層
化に伴って、磁気記録層を形成するための基体を改良す
る試みが種々行われており、ベースフィルム等の非磁性
支持体上にヘマタイト粒子や含水酸化第二鉄粒子等の鉄
を主成分とする非磁性粒子粉末を結合剤中に分散させて
なる下地層（以下、非磁性下地層という。）を少なくと
も１層設けることが行われており、既に、実用化されて
いる（特公平６−９３２９７号公報、特開昭６２−１５
９３３８号公報、特開昭６３−１８７４１８号公報、特
開平４−１６７２２５号公報、特開平４−３２５９１５
公報、特開平５−７３８８２号公報、特開平５−１８２
１７７号公報、特開平５−３４７０１７号公報、特開平
６−６０３６２号公報等）。With the thinning of the magnetic recording layer and the thinning of the non-magnetic support, various attempts have been made to improve the base for forming the magnetic recording layer, and a non-magnetic support such as a base film has been developed. At least one underlayer (hereinafter, referred to as a nonmagnetic underlayer) formed by dispersing iron-based nonmagnetic particles such as hematite particles and ferric hydroxide particles in a binder is provided on the body. This has already been put to practical use (Japanese Patent Publication No. 6-93297, Japanese Patent Application Laid-Open No. 62-15 / 1987).
9338, JP-A-63-187418, JP-A-4-167225, JP-A-4-325915
JP-A-5-73882, JP-A-5-182
177, JP-A-5-347017, JP-A-6-60362, etc.).

【００１８】また、非磁性下地層用の非磁性粒子粉末と
しては、ビヒクル中への分散性等を改善する目的で粒子
表面をジルコニウム化合物等で処理した非磁性粒子が知
られている（特許第２５６６０８８号公報、特許第２５
７１３５０号公報、特許第２５８２０５１号公報、特開
平６−６０３６２号公報、特開平９−２２５２４号公
報、特開平９−２７１１７号公報、特開平５−７３８８
３号公報、特開平６−６０３６０号公報、特開平８−５
０７１８号公報、特開平８−２５５３３４号公報、特開
平９−２７１１６号公報、特開平９−２７１１７号公
報、特開平９−３５２４５号公報）。As a non-magnetic particle powder for a non-magnetic underlayer, non-magnetic particles having a particle surface treated with a zirconium compound or the like for the purpose of improving the dispersibility in a vehicle, etc., are known (Japanese Patent No. 284,028). Japanese Patent No. 25666088, Patent No. 25
No. 71350, Japanese Patent No. 2582051, JP-A-6-60362, JP-A-9-22524, JP-A-9-27117, JP-A-5-7388
No. 3, JP-A-6-60360, JP-A-8-5
0718, JP-A-8-255334, JP-A-9-27116, JP-A-9-27117 and JP-A-9-35245.

【００１９】[0019]

【発明が解決しようとする課題】磁気記録層の薄層化は
もちろん、非磁性支持体の薄層化に伴って、光透過率が
小さく、表面平滑で、強度が大きく、且つ、耐久性が優
れている磁気記録媒体は、現在最も要求されているとこ
ろであるが、このような諸特性を十分満たす磁気記録媒
体は未だ得られていない。As the thickness of the magnetic recording layer is reduced, as well as the thickness of the nonmagnetic support, the light transmittance is low, the surface is smooth, the strength is high, and the durability is low. An excellent magnetic recording medium is currently most demanded, but a magnetic recording medium that sufficiently satisfies such characteristics has not yet been obtained.

【００２０】即ち、非磁性支持体上に非磁性粉末を結合
剤樹脂中に分散させた非磁性下地層を形成した基体を用
いて製造した磁気記録媒体は、光透過率が小さく、表面
が平滑で、強度が大きいものではあるが、耐久性が悪い
という問題があった。That is, a magnetic recording medium manufactured using a substrate having a non-magnetic underlayer formed by dispersing a non-magnetic powder in a binder resin on a non-magnetic support has a low light transmittance and a smooth surface. Thus, although the strength is high, there is a problem that the durability is poor.

【００２１】この事実は、特開平５−１８２１７７号公
報の「‥‥支持体表面の非磁性の厚い下塗層を設けてか
ら磁性層を上層として設けるようにすれば前記の支持体
の表面粗さの影響は解消することができるが、ヘッド磨
耗や耐久性が改善されないという問題があった。これ
は、従来、非磁性下層として熱硬化系樹脂を結合剤とし
て用いているので、下層が硬化し、磁性層とヘッドとの
摩擦や他の部材との接触が無緩衝状態で行われること
や、このような下層を有する磁気記録媒体がやや可撓性
に乏しい等のことに起因していると考えられる。‥‥」
なる記載の通りである。This fact is described in Japanese Unexamined Patent Publication No. Hei 5-182177, "‥‥ If the non-magnetic thick undercoat layer is provided on the support surface and then the magnetic layer is provided as the upper layer, the surface roughness of the support can be improved. However, there is a problem that the wear and durability of the head are not improved because the thermosetting resin is used as the binder as the non-magnetic lower layer so that the lower layer is hardened. However, this is because friction between the magnetic layer and the head and contact with other members are performed in an unbuffered state, and the magnetic recording medium having such a lower layer is slightly less flexible. it is conceivable that.‥‥"
It is as described.

【００２２】そこで、本発明は、光透過率が小さく、表
面平滑で、強度が大きく、且つ、耐久性に優れた磁気記
録媒体を得ることを技術的課題とする。Therefore, an object of the present invention is to provide a magnetic recording medium having a small light transmittance, a smooth surface, a high strength, and excellent durability.

【００２３】[0023]

【課題を解決する為の手段】前記技術的課題は、次の通
りの本発明によって達成できる。The above technical object can be achieved by the present invention as described below.

【００２４】即ち、本発明は、非磁性支持体と該非磁性
支持体上に形成される非磁性粒子粉末と結合剤樹脂とを
含む非磁性下地層とからなる磁気記録媒体用基体におい
て、前記非磁性粒子粉末はＺｒ換算で０．０５〜３０重
量％のジルコニウムを粒子内部に含有している鉄を主成
分とする針状非磁性粒子粉末、必要により、更に、アル
ミニウムの水酸化物、アルミニウムの酸化物、ケイ素の
水酸化物及びケイ素の酸化物の少なくとも１種で粒子表
面が被覆されている鉄を主成分とする針状非磁性粒子か
らなることを特徴とする非磁性下地層を有する磁気記録
媒体用基体である。That is, the present invention provides a magnetic recording medium substrate comprising a non-magnetic support and a non-magnetic underlayer containing a non-magnetic particle powder and a binder resin formed on the non-magnetic support. The magnetic particle powder is an acicular non-magnetic particle powder containing iron as a main component containing 0.05 to 30% by weight of zirconium in the interior of the particle in terms of Zr. A magnetic material having a non-magnetic underlayer, comprising needle-shaped non-magnetic particles containing iron as a main component and having a particle surface coated with at least one of oxide, silicon hydroxide and silicon oxide. This is a recording medium base.

【００２５】また、本発明は、前記非磁性下地層を有す
る磁気記録媒体用基体の上に、磁性粒子粉末と結合剤樹
脂とを含む磁気記録層を設けた磁気記録媒体である。The present invention also provides a magnetic recording medium comprising a magnetic recording medium having a nonmagnetic underlayer, and a magnetic recording layer containing magnetic particles and a binder resin provided on the magnetic recording medium substrate.

【００２６】本発明の構成をより詳しく説明すれば、次
の通りである。The structure of the present invention will be described in more detail as follows.

【００２７】先ず、本発明に係る非磁性下地層を有する
磁気記録媒体用基体について述べる。First, the base for a magnetic recording medium having a nonmagnetic underlayer according to the present invention will be described.

【００２８】本発明における鉄を主成分とする非磁性粒
子粉末は、針状ゲータイト（α−ＦｅＯＯＨ）粒子等の
含水酸化第二鉄粒子粉末や針状ヘマタイト粒子粉末であ
り、これら粒子粉末は、Ｚｒ換算で０．０５〜３０重量
％のジルコニウムを粒子内部にほぼ均一に含有してい
る。The non-magnetic particles containing iron as a main component in the present invention are ferric hydroxide particles such as acicular goethite (α-FeOOH) particles or acicular hematite particles. Zirconium of 0.05 to 30% by weight in terms of Zr is almost uniformly contained inside the particles.

【００２９】粒子内部に含有されているジルコニウム量
が鉄を主成分とする針状非磁性粒子に対しＺｒ換算で
０．０５重量％未満の場合には、得られた磁気記録媒体
は十分な耐久性を有しない。３０重量％を越える場合に
は、得られた磁気記録媒体は十分な耐久性を有している
が、効果が飽和するため必要以上に含有させる意味がな
い。磁気記録媒体の耐久性を考慮すると０．５〜２５重
量％が好ましい。より好ましくは１．０〜２０重量％で
ある。When the amount of zirconium contained in the particles is less than 0.05% by weight in terms of Zr with respect to the acicular nonmagnetic particles containing iron as a main component, the obtained magnetic recording medium has sufficient durability. Does not have the property. When the content exceeds 30% by weight, the obtained magnetic recording medium has sufficient durability, but the effect is saturated and there is no point in containing more than necessary. Considering the durability of the magnetic recording medium, the content is preferably 0.5 to 25% by weight. More preferably, it is 1.0 to 20% by weight.

【００３０】本発明における鉄を主成分とする針状非磁
性粒子粉末は、軸比（平均長軸径：平均短軸径、以下、
単に「軸比」という。）が２：１以上、好ましくは３：
１以上の粒子が好ましい。ビヒクル中での分散性を考慮
すれば、その上限値は、２０：１以下、好ましくは１
０：１以下の粒子が好ましい。ここで、針状粒子とは、
針状はもちろん、紡錘状、米粒状等を含む意味である。The acicular nonmagnetic particle powder containing iron as a main component in the present invention has an axial ratio (average major axis diameter: average minor axis diameter;
Simply referred to as "axial ratio". ) Is at least 2: 1, preferably 3:
One or more particles are preferred. Considering the dispersibility in the vehicle, the upper limit is 20: 1 or less, preferably 1: 1.
Particles of 0: 1 or less are preferred. Here, the acicular particles are
Needle-shaped, as well as spindle-shaped, rice-granular, etc. are meant.

【００３１】軸比が２：１未満の場合には、所望の塗膜
強度が得られ難くなる。When the axial ratio is less than 2: 1, it becomes difficult to obtain a desired coating film strength.

【００３２】本発明における鉄を主成分とする針状非磁
性粒子粉末の平均長軸径は０．３μｍ以下である。平均
長軸径が０．３μｍを越える場合には、粒子サイズが大
きすぎる為、塗膜の表面平滑性を害するので好ましくな
い。鉄を主成分とする針状非磁性粒子の平均長軸径が
０．００５μｍ未満の場合には、ビヒクル中における分
散が困難となるので好ましくない。ビヒクル中における
分散性及び塗膜の表面平滑性を考慮すれば０．０２〜
０．２μｍが好ましい。The average major axis diameter of the acicular nonmagnetic particle powder containing iron as a main component in the present invention is 0.3 μm or less. If the average major axis diameter exceeds 0.3 μm, the particle size is too large, which impairs the surface smoothness of the coating film. If the average major axis diameter of the acicular nonmagnetic particles containing iron as a main component is less than 0.005 μm, dispersion in a vehicle becomes difficult, which is not preferable. Considering the dispersibility in the vehicle and the surface smoothness of the coating film, 0.02
0.2 μm is preferred.

【００３３】本発明における鉄を主成分とする針状非磁
性粒子粉末は、平均短軸径が０．００２５〜０．１５μ
ｍが好ましい。０．００２５μｍ未満の場合には、ビヒ
クル中における分散が困難となるので好ましくない。平
均短軸径が０．１５μｍを越える場合には、粒子サイズ
が大きすぎる為、塗膜の表面平滑性を害するので好まし
くない。ビヒクル中における分散性及び塗膜の表面平滑
性を考慮すれば０．０１〜０．１０μｍが好ましい。The acicular nonmagnetic particles containing iron as a main component according to the present invention have an average minor axis diameter of 0.0025 to 0.15 μm.
m is preferred. If it is less than 0.0025 μm, dispersion in the vehicle becomes difficult, which is not preferable. If the average minor axis diameter exceeds 0.15 μm, the particle size is too large, which impairs the surface smoothness of the coating film, which is not preferable. Considering the dispersibility in the vehicle and the surface smoothness of the coating film, the thickness is preferably 0.01 to 0.10 μm.

【００３４】本発明における鉄を主成分とする針状非磁
性粒子粉末としての針状ゲータイト粒子粉末は、ＢＥＴ
比表面積値が５０ｍ2 ／ｇ以上であることが好ましい。
５０ｍ2 ／ｇ未満の場合には、塗膜の表面平滑化に悪影
響を与えるので好ましくない。好ましくは７０ｍ2 ／ｇ
以上、より好ましくは８０ｍ2 ／ｇ以上であり、その上
限値は３００ｍ2 ／ｇである。ビヒクル中における分散
性を考慮すると好ましくは２５０ｍ2 ／ｇ以下、より好
ましくは２００ｍ2 ／ｇ以下である。The acicular goethite particle powder as the acicular nonmagnetic particle powder containing iron as a main component in the present invention is a BET.
It is preferable that the specific surface area value be 50 m 2 / g or more.
If it is less than 50 m 2 / g, the surface smoothness of the coating film is adversely affected, which is not preferable. Preferably 70 m 2 / g
As described above, it is more preferably 80 m 2 / g or more, and the upper limit is 300 m 2 / g. Considering the dispersibility in the vehicle, it is preferably at most 250 m 2 / g, more preferably at most 200 m 2 / g.

【００３５】本発明における鉄を主成分とする針状非磁
性粒子粉末としての針状ヘマタイト粒子粉末は、ＢＥＴ
比表面積値が３５ｍ2 ／ｇ以上であることが好ましい。
３５ｍ2 ／ｇ未満の場合には、ヘマタイト粒子が粗大で
あったり、粒子及び粒子相互間で焼結が生じた粒子とな
っており、塗膜の表面平滑化に悪影響を与えるので好ま
しくない。好ましくは４０ｍ2 ／ｇ以上、より好ましく
は４５ｍ2 ／ｇ以上であり、その上限値は３００ｍ2 ／
ｇである。ビヒクル中における分散性を考慮すると好ま
しくは１００ｍ2 ／ｇ以下、より好ましくは８０ｍ2 ／
ｇ以下である。The acicular hematite particle powder as the acicular nonmagnetic particle powder containing iron as a main component in the present invention is a BET.
The specific surface area value is preferably 35 m 2 / g or more.
If it is less than 35 m 2 / g, the hematite particles are coarse, or the particles are sintered between the particles, which adversely affects the surface smoothness of the coating film, which is not preferable. Preferably 40 m 2 / g or more, more preferably 45 m 2 / g or more, its upper limit is 300 meters 2 /
g. Considering the dispersibility in vehicle preferably 100 m 2 / g or less, more preferably 80 m 2 /
g or less.

【００３６】本発明における鉄を主成分とする針状非磁
性粒子粉末は、長軸径の粒度分布が幾何標準偏差値で
１．５０以下であることが好ましい。１．５０を越える
場合には、存在する粗大粒子が塗膜の表面平滑化に悪影
響を与えるので好ましくない。塗膜の表面平滑性を考慮
すれば、好ましくは１．４０以下、より好ましくは１．
３５以下である。工業的な生産性を考慮すれば、得られ
る鉄を主成分とする針状非磁性粒子の長軸径の粒度分布
の下限値は、幾何標準偏差値で１．０１である。The iron-based acicular nonmagnetic particles according to the present invention preferably have a major axis diameter particle size distribution of 1.50 or less in terms of geometric standard deviation. If it exceeds 1.50, the presence of coarse particles adversely affects the surface smoothness of the coating film, which is not preferable. Considering the surface smoothness of the coating film, it is preferably 1.40 or less, more preferably 1.40.
35 or less. In view of industrial productivity, the lower limit of the particle size distribution of the major axis diameter of the obtained acicular nonmagnetic particles containing iron as a main component is 1.01 as a geometric standard deviation.

【００３７】本発明における鉄を主成分とする針状非磁
性粒子は、樹脂吸着強度が６０％以上であり、好ましく
は６５％以上であり、より好ましくは６８％以上であ
る。The needle-shaped nonmagnetic particles containing iron as a main component in the present invention have a resin adsorption strength of 60% or more, preferably 65% or more, more preferably 68% or more.

【００３８】本発明における針状ヘマタイト粒子は、密
度化の程度をＢＥＴ法により測定した比表面積ＳBET 値
と電子顕微鏡写真に示されている粒子から計測された長
軸径及び短軸径から算出した比表面積ＳTEM 値との比で
示した場合、０．５〜２．５を有しているものが好まし
い。塗膜の表面平滑性及びビヒクル中における分散性を
考慮するとＳBET ／ＳTEM の値は０．７〜２．０が好ま
しく、より好ましくは０．８〜１．６である。The acicular hematite particles in the present invention are calculated from the specific surface area S BET value measured by the BET method and the major axis diameter and the minor axis diameter measured from the particles shown in the electron micrograph. In the case where the ratio of the specific surface area to the determined specific surface area S TEM value is used, those having 0.5 to 2.5 are preferable. In consideration of the surface smoothness of the coating film and the dispersibility in the vehicle, the value of S BET / S TEM is preferably from 0.7 to 2.0, more preferably from 0.8 to 1.6.

【００３９】本発明における鉄を主成分とする針状非磁
性粒子は、必要により、アルミニウムの水酸化物、アル
ミニウムの酸化物、ケイ素の水酸化物及びケイ素の酸化
物の少なくとも１種で粒子表面が被覆されていてもよ
い。粒子表面がこれら表面被覆物で被覆されている鉄を
主成分とする針状非磁性粒子は、結合剤樹脂とのなじみ
がよいので、ビヒクル中における分散性が優れたものと
なる。The needle-shaped nonmagnetic particles containing iron as a main component according to the present invention may comprise, if necessary, at least one of aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide. May be coated. The needle-shaped non-magnetic particles whose main component is iron and whose particle surfaces are coated with these surface coatings have good compatibility with the binder resin, and therefore have excellent dispersibility in the vehicle.

【００４０】上記表面被覆物の量は、アルミニウムの水
酸化物やアルミニウムの酸化物の場合はＡｌ換算で、ケ
イ素の水酸化物やケイ素の酸化物の場合はＳｉＯ2 換算
で粒子の全重量に対し０．０１〜５０重量％が好まし
い。０．０１重量％未満である場合には、被覆による分
散性向上効果が得られ難く、５０重量％を越える場合に
は、被覆効果が飽和するため、必要以上に添加する意味
がない。ビヒクル中における分散性を考慮すれば、０．
０５〜２０重量％がより好ましい。The amount of the surface coating is based on the total weight of the particles in terms of Al in the case of aluminum hydroxide or aluminum oxide, and in terms of SiO 2 in the case of silicon hydroxide or silicon oxide. On the other hand, the content is preferably 0.01 to 50% by weight. When the amount is less than 0.01% by weight, the effect of improving the dispersibility by coating is difficult to be obtained, and when the amount exceeds 50% by weight, the effect of coating is saturated, so that there is no point in adding more than necessary. Considering the dispersibility in the vehicle, 0.
More preferably, the content is from 0.5 to 20% by weight.

【００４１】粒子表面が表面被覆物で被覆されている鉄
を主成分とする針状非磁性粒子粉末の軸比、平均長軸
径、平均短軸径、ＢＥＴ比表面積値、長軸径の粒度分
布、樹脂吸着強度及び密度化の程度は、表面被覆物で被
覆されていない鉄を主成分とする針状非磁性粒子粉末と
ほぼ同じである。Axial ratio, average major axis diameter, average minor axis diameter, BET specific surface area value, particle diameter of major axis diameter of needle-like nonmagnetic particle powder containing iron as a main component whose surface is coated with a surface coating The distribution, the resin adsorption strength and the degree of densification are almost the same as those of the acicular nonmagnetic particle powder mainly composed of iron not covered with the surface coating.

【００４２】本発明における非磁性下地層は、非磁性支
持体上に形成されており、鉄を主成分とする針状非磁性
粒子粉末と結合剤樹脂とからなる。The non-magnetic underlayer in the present invention is formed on a non-magnetic support, and is composed of acicular non-magnetic particle powder containing iron as a main component and a binder resin.

【００４３】非磁性支持体としては、現在、磁気記録媒
体に汎用されているポリエチレンテレフタレート、ポリ
エチレン、ポリプロピレン、ポリカーボネート、ポリエ
チレンナフタレート、ポリアミド、ポリアミドイミド、
ポリイミド等の合成樹脂フィルム、アルミニウム、ステ
ンレス等金属の箔や板および各種の紙を使用することが
でき、その厚みは、材質により種々異なるが、通常１．
０〜３００μｍ、より好ましくは２．０〜２００μｍの
ものが用いられている。磁気ディスクの場合は、非磁性
支持体としてポリエチレンテレフタレートが通常用いら
れ、その厚みは、通常５０〜３００μｍ、好ましくは６
０〜２００μｍである。磁気テープの場合、その厚みは
材質により異なり、ポリエチレンテレフタレートの場合
は、通常３〜１００μｍ、好ましくは４〜２０μｍであ
り、ポリエチレンナフタレートの場合は、通常３〜５０
μｍ、好ましくは４〜２０μｍであり、ポリアミドの場
合は、通常２〜１０μｍ、好ましくは３〜７μｍであ
る。Examples of the non-magnetic support include polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyethylene naphthalate, polyamide, polyamide imide, which are currently widely used for magnetic recording media.
Synthetic resin films such as polyimide, foils and plates of metals such as aluminum and stainless steel, and various types of paper can be used. The thickness varies depending on the material.
Those having a thickness of 0 to 300 μm, more preferably 2.0 to 200 μm are used. In the case of a magnetic disk, polyethylene terephthalate is usually used as a nonmagnetic support, and its thickness is usually 50 to 300 μm, preferably 6 to 300 μm.
0 to 200 μm. In the case of a magnetic tape, its thickness varies depending on the material. In the case of polyethylene terephthalate, it is usually 3 to 100 μm, preferably 4 to 20 μm, and in the case of polyethylene naphthalate, it is usually 3 to 50 μm.
μm, preferably 4 to 20 μm, and in the case of polyamide, it is usually 2 to 10 μm, preferably 3 to 7 μm.

【００４４】本発明における非磁性支持体上に形成され
た非磁性下地層の塗膜厚さは、０．２〜１０．０μｍの
範囲である。０．２μｍ未満の場合には、非磁性支持体
の表面粗さを改善することが困難となり、強度も不十分
になりやすい。薄層の磁気記録媒体を得るためには上限
値は１０．０μｍ程度が好ましく、より好ましくは０．
５〜５．０μｍの範囲である。The coating thickness of the nonmagnetic underlayer formed on the nonmagnetic support in the present invention is in the range of 0.2 to 10.0 μm. If it is less than 0.2 μm, it becomes difficult to improve the surface roughness of the non-magnetic support, and the strength tends to be insufficient. In order to obtain a magnetic recording medium having a thin layer, the upper limit is preferably about 10.0 μm, more preferably 0.1 μm.
It is in the range of 5 to 5.0 μm.

【００４５】結合剤樹脂としては、現在、磁気記録媒体
の製造にあたって汎用されている塩化ビニル−酢酸ビニ
ル共重合樹脂、ウレタン樹脂、塩化ビニル−酢酸ビニル
−マレイン酸共重合樹脂、ウレタンエラストマー、ブタ
ジエン−アクリロニトリル共重合樹脂、ポリビニルブチ
ラール、ニトロセルロース等セルロース誘導体、ポリエ
ステル樹脂、ポリブタジエン等の合成ゴム系樹脂、エポ
キシ樹脂、ポリアミド樹脂、ポリイソシアネートポリマ
ー、電子線硬化型アクリルウレタン樹脂等とその混合物
を使用することができる。また、各結合剤樹脂には−Ｏ
Ｈ、−ＣＯＯＨ、−ＳＯ3 Ｍ、−ＯＰＯ2 Ｍ2 、−ＮＨ
2 等の極性基（但し、ＭはＨ、Ｎａ、Ｋである。）が含
まれていてもよい。粒子の分散性を考慮すれば、極性基
−ＣＯＯＨ、−ＳＯ3 Ｍが含まれている結合剤樹脂が好
ましい。Examples of the binder resin include vinyl chloride-vinyl acetate copolymer resins, urethane resins, vinyl chloride-vinyl acetate-maleic acid copolymer resins, urethane elastomers, butadiene resins commonly used in the production of magnetic recording media. Use of acrylonitrile copolymer resin, cellulose derivatives such as polyvinyl butyral, nitrocellulose, synthetic rubber resins such as polyester resin and polybutadiene, epoxy resin, polyamide resin, polyisocyanate polymer, electron beam curable acrylic urethane resin and the like and mixtures thereof. Can be. In addition, each binder resin has -O
H, -COOH, -SO 3 M, -OPO 2 M 2, -NH
A polar group such as 2 (however, M is H, Na, or K) may be contained. Considering dispersibility of the particles, the polar group -COOH, binder resins that contain -SO 3 M are preferable.

【００４６】非磁性下地層における鉄を主成分とする針
状非磁性粒子粉末と結合剤樹脂との配合割合は、結合剤
樹脂１００重量部に対し、鉄を主成分とする針状非磁性
粒子が５〜２０００重量部、好ましくは１００〜１００
０重量部である。The mixing ratio of the powder of the needle-shaped non-magnetic particles containing iron as the main component and the binder resin in the non-magnetic underlayer is such that the needle-shaped non-magnetic particles containing iron as the main component are contained in 100 parts by weight of the binder resin. Is 5 to 2000 parts by weight, preferably 100 to 100 parts by weight.
0 parts by weight.

【００４７】尚、非磁性下地層に、通常の磁気記録媒体
の製造に用いられる潤滑剤、研磨剤、帯電防止剤等が必
要により含まれていてもよい。Incidentally, the non-magnetic underlayer may contain a lubricant, an abrasive, an antistatic agent, and the like, which are used for manufacturing a normal magnetic recording medium, if necessary.

【００４８】本発明における鉄を主成分とする針状非磁
性粒子粉末を含有する非磁性下地層は、塗膜の光沢度が
１７０〜２８０％、好ましくは１８０〜２８０％、より
好ましくは１８５〜２８０％、塗膜表面粗度Ｒａが２．
０〜１５．０ｎｍ、好ましくは２．０〜１３．０ｎｍ、
より好ましくは２．０〜１２．０ｎｍ、ヤング率が１２
５〜１５０、好ましくは１２７〜１５０、より好ましく
は１３０〜１５０である。The nonmagnetic underlayer containing the iron-based acicular nonmagnetic particle powder according to the present invention has a glossiness of the coating film of 170 to 280%, preferably 180 to 280%, more preferably 185 to 280%. 280%, coating film surface roughness Ra is 2.
0-15.0 nm, preferably 2.0-13.0 nm,
More preferably, 2.0-12.0 nm, Young's modulus is 12
It is 5-150, preferably 127-150, more preferably 130-150.

【００４９】次に、本発明に係る磁気記録媒体について
述べる。Next, the magnetic recording medium according to the present invention will be described.

【００５０】磁気記録媒体は、非磁性支持体上に形成さ
れた非磁性下地層の上に、磁性粒子粉末と結合剤樹脂か
らなる磁気記録層が設けられている。The magnetic recording medium has a magnetic recording layer made of magnetic particle powder and a binder resin on a non-magnetic underlayer formed on a non-magnetic support.

【００５１】本発明における磁性粒子粉末は、マグヘマ
イト粒子粉末、マグネタイト粒子粉末、マグヘマイトと
マグネタイトとの中間酸化物であるベルトライド化合物
粒子等の磁性酸化鉄粒子粉末、これらの磁性酸化鉄粒子
粉末にＦｅ以外にＣｏ、Ａｌ、Ｎｉ、Ｐ、Ｚｎ、Ｓｉ、
Ｂ等の異種元素を含有させた粒子若しくはこれら磁性酸
化鉄粒子にＣｏ等を被着させた粒子、鉄を主成分とする
金属磁性粒子、鉄以外のＣｏ、Ａｌ、Ｎｉ、Ｐ、Ｚｎ、
Ｓｉ、Ｂ等を含有する鉄合金磁性粒子、板状Ｂａフェラ
イト粒子粉末並びにこれに保磁力低減剤である２価金属
（Ｃｏ、Ｎｉ、Ｚｎ等）と４価金属（Ｔｉ、Ｓｎ、Ｚｒ
等）とを含有させた板状複合フェライト粒子粉末等のい
ずれも用いることができる。また、磁性粒子粉末は、平
均長軸径が０．０１〜０．５０μｍ、好ましくは０．０
３〜０．３０μｍであって、平均短軸径が０．０００７
〜０．１７μｍ、好ましくは０．００３〜０．１０μｍ
であって、軸比が３：１以上、好ましくは５：１以上の
粒子が好ましい。ビヒクル中での分散性を考慮すれば、
軸比の上限値は、１５：１以下、好ましくは１０：１以
下である。粒子の形状は、針状はもちろん、紡錘状、米
粒状、立方状、板状等のいずれでであってもよい。The magnetic particles according to the present invention include maghemite particles, magnetite particles, magnetic iron oxide particles such as belt oxide compound particles which are intermediate oxides between maghemite and magnetite, and the like. Besides, Co, Al, Ni, P, Zn, Si,
Particles containing different elements such as B or particles obtained by applying Co or the like to these magnetic iron oxide particles, metal magnetic particles containing iron as a main component, Co, Al, Ni, P, Zn other than iron,
Iron alloy magnetic particles containing Si, B, etc., plate-like Ba ferrite particles, and divalent metals (Co, Ni, Zn, etc.) as coercive force reducing agents and tetravalent metals (Ti, Sn, Zr)
) Can be used. The magnetic particle powder has an average major axis diameter of 0.01 to 0.50 μm, preferably 0.0
3 to 0.30 μm, and the average minor axis diameter is 0.0007.
０．１0.17 μm, preferably 0.003 to 0.10 μm
And particles having an axial ratio of 3: 1 or more, preferably 5: 1 or more are preferred. Considering the dispersibility in the vehicle,
The upper limit of the axial ratio is 15: 1 or less, preferably 10: 1 or less. The shape of the particles may be any of a spindle shape, a rice grain shape, a cubic shape, a plate shape, and the like, as well as a needle shape.

【００５２】本発明における磁性粒子粉末の磁気特性
は、高密度記録化等の諸特性を考慮すれば、保磁力は３
００〜３２００Ｏｅが好ましく、より好ましくは７００
〜２５００Ｏｅであり、飽和磁化は６０〜１７０ｅｍｕ
／ｇが好ましく、より好ましくは７０〜１７０ｅｍｕ／
ｇである。The magnetic properties of the magnetic particles according to the present invention are 3 coercive forces in consideration of various properties such as high density recording.
00-3200 Oe is preferable, and more preferably 700
２2500 Oe, and the saturation magnetization is 60-170 emu.
/ G is preferred, and more preferably 70 to 170 emu /
g.

【００５３】磁気記録層における結合剤樹脂には、非磁
性下地層を形成するのに用いた前記結合剤樹脂を使用す
ることができる。As the binder resin in the magnetic recording layer, the binder resin used for forming the nonmagnetic underlayer can be used.

【００５４】非磁性下地層上に設けられた磁気記録層の
塗膜厚さは、０．０１〜５．０μｍの範囲である。０．
０１μｍ未満の場合には、均一な塗布が困難で塗りむら
等が生じやすくなるため好ましくない。５．０μｍを越
える場合には、反磁界の影響のため、磁気記録媒体の電
磁変換特性が得られにくくなる。好ましくは０．０５〜
１．０μｍの範囲である。The coating thickness of the magnetic recording layer provided on the nonmagnetic underlayer is in the range of 0.01 to 5.0 μm. 0.
When the thickness is less than 01 μm, it is not preferable because uniform coating is difficult and uneven coating is likely to occur. If it exceeds 5.0 μm, it becomes difficult to obtain the electromagnetic conversion characteristics of the magnetic recording medium due to the influence of the demagnetizing field. Preferably 0.05 to
The range is 1.0 μm.

【００５５】磁気記録層における磁性粒子粉末と結合剤
樹脂との配合割合は、結合剤樹脂１００重量部に対し、
磁性粒子粉末が２００〜２０００重量部、好ましくは３
００〜１５００重量部である。The mixing ratio of the magnetic particle powder and the binder resin in the magnetic recording layer is based on 100 parts by weight of the binder resin.
200 to 2000 parts by weight, preferably 3 parts by weight of magnetic particles
It is 00 to 1500 parts by weight.

【００５６】磁気記録層中には、通常用いられる潤滑
剤、研磨剤、帯電防止剤等が必要により含まれていても
よい。The magnetic recording layer may contain a commonly used lubricant, abrasive, antistatic agent, and the like, if necessary.

【００５７】本発明に係る磁気記録媒体は、保磁力が３
００〜３５００Ｏｅ、好ましくは５００〜３５００Ｏ
ｅ、より好ましくは７００〜３５００Ｏｅ、角形比（残
留磁束密度Ｂｒ／飽和磁束密度Ｂｍ）が０．８５〜０．
９５、好ましくは０．８６〜０．９５、塗膜の光沢度が
１８０〜３００％、好ましくは１９０〜３００％、塗膜
表面粗度Ｒａが１２．０ｎｍ以下、好ましくは２．０〜
１１．０ｎｍ、より好ましくは２．０〜１０．０ｎｍ、
ヤング率は１３０以上、好ましくは１３２以上、塗膜の
線吸収係数が１．１０〜２．００μｍ-1好ましくは１．
２０〜２．００μｍ-1、耐久性のうち走行耐久性は１５
分以上、好ましくは２０分以上、さらに好ましくは２２
分以上であり、すり傷性はＢ以上、好ましくはＡであ
る。The magnetic recording medium according to the present invention has a coercive force of 3
00-3500 Oe, preferably 500-3500 Oe
e, more preferably 700 to 3500 Oe, and a squareness ratio (residual magnetic flux density Br / saturated magnetic flux density Bm) of 0.85 to 0.8.
95, preferably 0.86 to 0.95, the glossiness of the coating film is 180 to 300%, preferably 190 to 300%, and the coating film surface roughness Ra is 12.0 nm or less, preferably 2.0 to
11.0 nm, more preferably 2.0 to 10.0 nm,
The Young's modulus is 130 or more, preferably 132 or more, and the linear absorption coefficient of the coating film is 1.10 to 2.00 µm -1, preferably 1.
20-2.00 μm −1 , of which the running durability is 15
Minutes or more, preferably 20 minutes or more, more preferably 22 minutes or more.
Min or more, and the abrasion is B or more, preferably A.

【００５８】次に、本発明における鉄を主成分とする針
状非磁性粒子粉末であるとともに、針状ヘマタイト粒子
の出発原料でもある粒子内部にジルコニウムをほぼ均一
に含有している針状ゲータイト粒子粉末の製造法につい
て述べる。Next, acicular goethite particles containing the zirconium substantially uniformly inside the acicular nonmagnetic particle powder containing iron as the main component and zirconium as the starting material of the acicular hematite particles in the present invention. The method for producing the powder will be described.

【００５９】粒子内部にジルコニウムをほぼ均一に含有
している針状ゲータイト粒子は、後に詳述する通り、第
一鉄塩水溶液と水酸化アルカリ水溶液、炭酸アルカリ水
溶液又は水酸化アルカリ・炭酸アルカリ水溶液のいずれ
かとを用いて反応して得られる鉄の水酸化物や炭酸鉄等
の鉄含有沈澱物を含む懸濁液に空気等の酸素含有ガスを
通気して針状ゲータイト粒子を生成させるにあたり、上
記懸濁液中に空気等の酸素含有ガスを通気する前にジル
コニウム化合物をＦｅに対しＺｒ換算で０．０４ｍｏｌ
％から４０ｍｏｌ％存在させておくことにより得ること
ができる。The acicular goethite particles containing zirconium substantially uniformly inside the particles are, as described later in detail, a ferrous salt aqueous solution and an alkali hydroxide aqueous solution, an alkali carbonate aqueous solution or an alkali hydroxide / alkali carbonate aqueous solution. When passing an oxygen-containing gas such as air through a suspension containing an iron-containing precipitate such as iron hydroxide or iron carbonate obtained by reacting with any of the above, needle-like goethite particles are formed. Before passing an oxygen-containing gas such as air into the suspension, the zirconium compound is 0.04 mol in terms of Zr with respect to Fe.
% To 40 mol%.

【００６０】ジルコニウム化合物としては、硫酸ジルコ
ニウム、オキシ硫酸ジルコニウム、硝酸ジルコニウム、
酢酸ジルコニウム、塩化ジルコニウム等を使用すること
ができる。As the zirconium compound, zirconium sulfate, zirconium oxysulfate, zirconium nitrate,
Zirconium acetate, zirconium chloride and the like can be used.

【００６１】このようにして得られる針状ゲータイト粒
子は、粒子の中心部から粒子表面に至るまでジルコニウ
ムが実質的に均一に含有されている粒子である。The needle-like goethite particles thus obtained are particles containing zirconium substantially uniformly from the center of the particles to the surface of the particles.

【００６２】尚、針状ゲータイト粒子の代表的の基本反
応としては、第一鉄塩水溶液に当量以上の水酸化アル
カリ水溶液を加えて得られる水酸化第一鉄コロイドを含
む懸濁液をｐＨ値１１以上にて８０℃以下の温度で酸素
含有ガスを通気して酸化反応を行うことにより針状ゲー
タイト粒子を生成させる方法、第一鉄塩水溶液と炭酸
アルカリ水溶液とを反応させて得られるＦｅＣＯ3 を含
む懸濁液を、必要により熟成した後、酸素含有ガスを通
気して酸化反応を行うことにより紡錘状を呈したゲータ
イト粒子を生成させる方法、第一鉄塩水溶液と炭酸ア
ルカリ・水酸化アルカリ水溶液とを反応させて得られる
鉄含有沈澱物を含む懸濁液を、必要により熟成した後、
酸素含有ガスを通気して酸化反応を行うことにより紡錘
状を呈したゲータイト粒子を生成させる方法、第一鉄
塩水溶液に当量未満の水酸化アルカリ水溶液又は炭酸ア
ルカリ水溶液を添加して得られる水酸化第一鉄コロイド
を含む第一鉄塩水溶液に酸素含有ガスを通気して酸化反
応を行うことにより針状ゲータイト核粒子を生成させ、
次いで、該針状ゲータイト核粒子を含む第一鉄塩水溶液
に、該第一鉄塩水溶液中のＦｅ2+に対し当量以上の水酸
化アルカリ水溶液を添加した後、酸素含有ガスを通気し
て前記針状ゲータイト核粒子を成長させる方法、第一
鉄塩水溶液に当量未満の水酸化アルカリ水溶液又は炭酸
アルカリ水溶液を添加して得られる水酸化第一鉄コロイ
ドを含む第一鉄塩水溶液に酸素含有ガスを通気して酸化
反応を行うことにより針状ゲータイト核粒子を生成さ
せ、次いで、該針状ゲータイト核粒子を含む第一鉄塩水
溶液に、該第一鉄塩水溶液中のＦｅ2+に対し当量以上の
炭酸アルカリ水溶液を添加した後、酸素含有ガスを通気
して前記針状ゲータイト核粒子を成長させる方法及び
第一鉄塩水溶液と当量未満の水酸化アルカリ又は炭酸ア
ルカリ水溶液を添加して得られる水酸化第一鉄コロイド
を含む第一鉄塩水溶液に酸素含有ガスを通気して酸化反
応を行うことにより針状ゲータイト核粒子を生成させ、
次いで、酸性乃至中性領域で前記針状ゲータイト核粒子
を成長させる方法等がある。As a typical basic reaction of acicular goethite particles, a suspension containing a ferrous hydroxide colloid obtained by adding an equivalent amount or more of an aqueous alkali hydroxide solution to a ferrous salt aqueous solution is used. A method of producing needle-like goethite particles by carrying out an oxidation reaction by passing an oxygen-containing gas at a temperature of not less than 11 and not more than 80 ° C., FeCO 3 obtained by reacting an aqueous ferrous salt solution with an aqueous alkali carbonate solution A method of producing goethite particles in the form of spindles by oxidizing the suspension containing an oxygen-containing gas by aeration, if necessary, after aging the suspension, ferrous salt aqueous solution and alkali carbonate / alkali hydroxide After aging the suspension containing the iron-containing precipitate obtained by reacting with the aqueous solution, if necessary,
A method of producing spindle-shaped goethite particles by carrying out an oxidation reaction by passing an oxygen-containing gas, and a method of adding a less than equivalent aqueous solution of an alkali hydroxide or an aqueous solution of an alkali carbonate to an aqueous solution of ferrous salt to obtain a hydroxide. Needle-like goethite core particles are generated by performing an oxidation reaction by passing an oxygen-containing gas through a ferrous salt aqueous solution containing ferrous colloid,
Next, to the aqueous ferrous salt solution containing the acicular goethite core particles, after adding an aqueous solution of an alkali hydroxide equivalent to or more than Fe 2+ in the aqueous ferrous salt solution, the oxygen-containing gas was passed through to pass the oxygen-containing gas. A method of growing needle-like goethite core particles, an oxygen-containing gas in a ferrous salt aqueous solution containing a ferrous hydroxide colloid obtained by adding a less than equivalent aqueous alkali hydroxide solution or an aqueous alkali carbonate solution to a ferrous salt aqueous solution To generate needle-like goethite core particles by performing an oxidation reaction, and then, to an aqueous ferrous salt solution containing the needle-like goethite core particles, an equivalent weight of Fe 2+ in the aqueous ferrous salt solution. After adding the aqueous alkali carbonate solution, a method of growing the needle-like goethite core particles by passing an oxygen-containing gas and adding an aqueous solution of an alkali hydroxide or an alkali carbonate less than the equivalent of a ferrous salt aqueous solution. To produce acicular goethite nucleus particles by performing aeration to oxidation an oxygen-containing gas into the aqueous ferrous salt solution containing ferrous hydroxide colloid for,
Next, there is a method of growing the acicular goethite core particles in an acidic to neutral region.

【００６３】次に、粒子内部にジルコニウムをほぼ均一
に含有している針状ヘマタイト粒子粉末の製造法につい
て述べる。Next, a method for producing acicular hematite particles containing zirconium substantially uniformly inside the particles will be described.

【００６４】粒子内部にジルコニウムをほぼ均一に含有
している針状ヘマタイト粒子は、粒子内部にジルコニウ
ムをほぼ均一に含有している前記針状ゲータイト粒子を
加熱脱水することにより得ることができる。The acicular hematite particles containing zirconium substantially uniformly inside the particles can be obtained by heating and dehydrating the acicular goethite particles containing zirconium substantially uniformly inside the particles.

【００６５】加熱脱水温度は、２５０〜８００℃程度で
ある。得られる粒子内部にジルコニウムを均一に含有し
ている針状ヘマタイト粒子の密度化の程度を考慮すれ
ば、５５０〜８００℃で加熱脱水することにより高密度
化された針状ヘマタイト粒子がより好ましい。The heat dehydration temperature is about 250 to 800 ° C. Considering the degree of densification of acicular hematite particles containing zirconium uniformly inside the obtained particles, acicular hematite particles which are densified by heating and dehydrating at 550 to 800 ° C. are more preferable.

【００６６】殊に、５５０℃以上の高温で加熱脱水する
場合には、周知の通り、針状ゲータイト粒子の加熱脱水
に先立ってあらかじめ針状ゲータイト粒子の粒子表面を
焼結防止剤で被覆しておくことが好ましい。In particular, in the case of heating and dehydrating at a high temperature of 550 ° C. or more, it is well known that the surface of the acicular goethite particles is coated with a sintering inhibitor before the thermal dehydration of the acicular goethite particles. Preferably.

【００６７】焼結防止剤としては、通常使用されるヘキ
サメタリン酸ナトリウム、ポリリン酸、オルトリン酸等
のリン化合物、３号水ガラス、オルトケイ酸ナトリウ
ム、メタケイ酸ナトリウム、コロイダルシリカ等のケイ
素化合物、ホウ酸等のホウ素化合物、酢酸アルミニウ
ム、硫酸アルミニウム、塩化アルミニウム、硝酸アルミ
ニウム等のアルミニウム塩や、アルミン酸ソーダ等のア
ルミン酸アルカリ塩、アルミナゾル、水酸化アルミニウ
ム等のアルミニウム化合物、オキシ硫酸チタン等のチタ
ン化合物を使用することができる。Examples of the sintering inhibitor include phosphorus compounds such as sodium hexametaphosphate, polyphosphoric acid and orthophosphoric acid which are commonly used, No. 3 water glass, silicon compounds such as sodium orthosilicate, sodium metasilicate and colloidal silica, and boric acid. Aluminum salts such as aluminum acetate, aluminum sulfate, aluminum chloride and aluminum nitrate, alkali aluminates such as sodium aluminate, aluminum compounds such as alumina sol and aluminum hydroxide, and titanium compounds such as titanium oxysulfate. Can be used.

【００６８】鉄を主成分とする針状非磁性粒子の表面に
存在する焼結防止剤の量は、粒子の全重量に対し０．０
５〜１０重量％程度が好ましい。The amount of the sintering inhibitor present on the surface of the acicular nonmagnetic particles containing iron as a main component is 0.0 to the total weight of the particles.
About 5 to 10% by weight is preferable.

【００６９】次に、本発明における針状非磁性粒子の粒
子表面を表面被覆物で被覆する方法について述べる。Next, a method for coating the particle surface of the acicular non-magnetic particles in the present invention with a surface coating will be described.

【００７０】被覆処理は、針状ゲータイト粒子や針状ヘ
マタイト粒子のケーキ、スラリー、乾燥粉末を水溶液中
に分散して得られる水懸濁液に、アルミニウム化合物、
ケイ素化合物又は当該両化合物を添加して混合攪拌する
ことにより、または、必要により、ｐＨ値を調整するこ
とにより、前記針状ヘマタイト粒子の粒子表面に、アル
ミニウムの水酸化物、アルミニウムの酸化物、ケイ素の
水酸化物及びケイ素の酸化物を被着し、次いで、濾別、
水洗、乾燥、粉砕すればよい。必要により、更に、脱気
・圧密処理等を施してもよい。In the coating treatment, an aluminum compound is added to a water suspension obtained by dispersing a cake, slurry, or dry powder of acicular goethite particles or acicular hematite particles in an aqueous solution.
By adding the silicon compound or both compounds and mixing and stirring, or if necessary, by adjusting the pH value, on the particle surface of the acicular hematite particles, a hydroxide of aluminum, an oxide of aluminum, Depositing silicon hydroxide and silicon oxide, followed by filtration,
It may be washed with water, dried, and pulverized. If necessary, a deaeration / consolidation treatment may be performed.

【００７１】被覆処理におけるアルミニウム化合物とし
ては、前出焼結防止剤と同じものが使用できる。As the aluminum compound in the coating treatment, the same aluminum compound as the above-mentioned sintering inhibitor can be used.

【００７２】アルミニウム化合物の添加量は、針状非磁
性粒子粉末に対しＡｌ換算で０．０１〜５０重量％であ
る。０．０１重量％未満である場合には、得られる針状
非磁性粒子粉末のアルミニウム化合物を被覆することで
期待される結合剤樹脂とのなじみが不十分であり、５０
重量％を越える場合には、被覆効果が飽和するため、必
要以上に添加する意味がない。The addition amount of the aluminum compound is 0.01 to 50% by weight in terms of Al with respect to the acicular nonmagnetic particle powder. When the amount is less than 0.01% by weight, the accommodating non-magnetic particles obtained are insufficiently compatible with the binder resin expected by coating the aluminum compound with the aluminum compound.
If the content is more than 10% by weight, the coating effect is saturated, and there is no point in adding more than necessary.

【００７３】被覆処理におけるケイ素化合物としては、
前出焼結防止剤と同じものが使用できる。As the silicon compound in the coating treatment,
The same sintering inhibitor as described above can be used.

【００７４】ケイ素化合物の添加量は、針状非磁性粒子
粉末に対しＳｉＯ2 換算で０．０１〜５０重量％であ
る。０．０１重量％未満である場合には、得られる針状
非磁性粒子粉末のケイ素化合物を被覆することで期待さ
れる結合剤樹脂とのなじみが不十分であり、５０重量％
を越える場合には、被覆効果が飽和するため、必要以上
に添加する意味がない。The addition amount of the silicon compound is 0.01 to 50% by weight in terms of SiO 2 with respect to the acicular nonmagnetic particle powder. When the amount is less than 0.01% by weight, the obtained acicular nonmagnetic particle powder is insufficiently blended with the binder resin expected by coating the silicon compound, and 50% by weight.
If it exceeds 3, the coating effect is saturated, and there is no point in adding more than necessary.

【００７５】アルミニウム化合物とケイ素化合物とを併
せて使用する場合には、針状非磁性粒子粉末に対し、Ａ
ｌ換算量とＳｉＯ2 換算量との総和で０．０１〜５０重
量％が好ましい。When an aluminum compound and a silicon compound are used in combination, A
It is preferable that the total amount of the amount in terms of 1 and the amount in terms of SiO 2 is 0.01 to 50% by weight.

【００７６】次に、本発明に係る非磁性下地層を有する
磁気記録媒体用基体の製造法について述べる。Next, a method for manufacturing a magnetic recording medium substrate having a nonmagnetic underlayer according to the present invention will be described.

【００７７】本発明に係る磁気記録媒体用基体は、非磁
性支持体上に鉄を主成分とする針状非磁性粒子粉末と結
合剤樹脂と溶剤とを含む非磁性塗料を塗布し塗膜を形成
した後、乾燥することにより得られる。The substrate for a magnetic recording medium according to the present invention is obtained by applying a nonmagnetic paint containing needle-like nonmagnetic particle powder containing iron as a main component, a binder resin and a solvent on a nonmagnetic support. After forming, it is obtained by drying.

【００７８】溶剤としては、現在磁気記録媒体の製造に
あたって汎用されているメチルエチルケトン、トルエ
ン、シクロヘキサノン、メチルイソブチルケトン、テト
ラヒドロフラン及びその混合物等を使用することができ
る。As the solvent, there can be used methyl ethyl ketone, toluene, cyclohexanone, methyl isobutyl ketone, tetrahydrofuran, a mixture thereof, and the like, which are currently widely used for producing magnetic recording media.

【００７９】溶剤の使用量は、非磁性粒子粉末１００重
量部に対しその総量で５０〜１０００重量部である。５
０重量部未満では非磁性塗料とした場合に粘度が高くな
りすぎ塗布が困難となる。１０００重量部を越える場合
には、塗膜を形成する際の溶剤の揮散量が多くなりすぎ
工業的に不利となる。The amount of the solvent used is 50 to 1000 parts by weight in total with respect to 100 parts by weight of the nonmagnetic particle powder. 5
If the amount is less than 0 parts by weight, the viscosity becomes too high when a non-magnetic paint is used, and application becomes difficult. If the amount exceeds 1,000 parts by weight, the amount of the solvent volatilized at the time of forming the coating film becomes too large, which is industrially disadvantageous.

【００８０】次に、本発明に係る磁気記録媒体の製造法
について述べる。Next, a method for manufacturing a magnetic recording medium according to the present invention will be described.

【００８１】本発明に係る磁気記録媒体は、非磁性下地
層上に、磁性粒子粉末と結合剤樹脂と溶剤とを含む塗膜
組成物を塗布し塗布膜を形成した後、乾燥して磁気記録
層を形成することにより得られる。In the magnetic recording medium according to the present invention, a coating composition containing magnetic particle powder, a binder resin and a solvent is applied on a nonmagnetic underlayer to form a coating film, which is then dried to form a magnetic recording medium. It is obtained by forming a layer.

【００８２】溶剤としては、現在磁気記録媒体の製造に
あたって汎用されているメチルエチルケトン、トルエ
ン、シクロヘキサノン、メチルイソブチルケトン、テト
ラヒドロフラン及びその混合物等を使用することができ
る。As the solvent, there can be used methyl ethyl ketone, toluene, cyclohexanone, methyl isobutyl ketone, tetrahydrofuran, a mixture thereof, and the like, which are currently widely used for producing magnetic recording media.

【００８３】溶剤の使用量は、磁性粒子粉末１００重量
部に対しその総量で６５〜１０００重量部である。６５
重量部未満では非磁性塗料とした場合に粘度が高くなり
すぎ塗布が困難となる。１０００重量部を越える場合に
は、塗膜を形成する際の溶剤の揮散量が多くなりすぎ工
業的に不利となる。The amount of the solvent used is 65 to 1000 parts by weight in total with respect to 100 parts by weight of the magnetic particle powder. 65
If the amount is less than part by weight, the viscosity becomes too high when a non-magnetic paint is used, and application becomes difficult. If the amount exceeds 1,000 parts by weight, the amount of the solvent volatilized at the time of forming the coating film becomes too large, which is industrially disadvantageous.

【００８４】[0084]

【発明の実施の形態】本発明の代表的な実施の形態は、
次の通りである。DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of the present invention is as follows.
It is as follows.

【００８５】粒子の平均長軸径、平均短軸径は、電子顕
微鏡写真（×３００００）を縦方向及び横方向にそれぞ
れ４倍に拡大した写真に示される粒子約３５０個につい
て長軸径、短軸径をそれぞれ測定し、その平均値で示し
た。軸比は、平均長軸径と平均短軸径との比である。The average major axis diameter and the average minor axis diameter of the particles were determined for the approximately 350 particles shown in the electron micrograph (× 30000) enlarged four times in the longitudinal and lateral directions, respectively, for about 350 particles. The shaft diameters were measured and indicated by the average value. The axis ratio is the ratio between the average major axis diameter and the average minor axis diameter.

【００８６】粒子の長軸径の幾何標準偏差値（σｇ）
は、下記の方法により求めた値で示した。即ち、上記拡
大写真に示される粒子の長軸径を測定した値を、その測
定値から計算して求めた粒子の実際の長軸径と個数から
統計学的手法に従って対数正規確率紙上に横軸に粒子の
長軸径を、縦軸に所定の長軸径区間のそれぞれに属する
粒子の累積個数（積算フルイ下）を百分率でプロットす
る。そして、このグラフから粒子の個数が５０％及び８
４．１３％のそれぞれに相当する長軸径の値を読みと
り、幾何標準偏差値（σｇ）＝積算フルイ下８４．１３
％における長軸径／積算フルイ下５０％における長軸径
（幾何平均径）に従って算出した値で示した。幾何標準
偏差値が小さい程、粒子の長軸径の粒度分布が優れてい
ることを意味する。Geometric standard deviation (σg) of the major axis diameter of the particles
Is indicated by a value obtained by the following method. That is, the value obtained by measuring the major axis diameter of the particles shown in the enlarged photograph is calculated from the measured major axis diameter and the actual number of the major axis diameter of the particles, and the horizontal axis is plotted on a lognormal probability paper according to a statistical method. Is plotted as the major axis diameter of the particles, and the ordinate is plotted as a percentage of the cumulative number of particles belonging to each of the predetermined major axis diameter sections (under the integrated screen). The graph shows that the number of particles is 50% and 8%.
The value of the major axis diameter corresponding to each of 4.13% was read, and the geometric standard deviation value (σg) = 84.13 below the integrated screen
% Calculated from the value of the major axis diameter in 50% / the major axis diameter (geometric mean diameter) at 50% below the integrated screen. The smaller the geometric standard deviation value, the better the particle size distribution of the major axis diameter of the particles.

【００８７】比表面積はＢＥＴ法により測定した値で示
した。The specific surface area was indicated by a value measured by the BET method.

【００８８】針状ヘマタイト粒子の密度化の程度は、前
述した通り、ＳBET ／ＳTEM で示した。ここで、ＳBET
は、上記ＢＥＴ法により測定した比表面積の値である。
ＳTEM は、前記電子顕微鏡写真から測定した粒子の平均
長軸径ｌｃｍ、平均短軸径ｗｃｍを用いて粒子を直方体
と仮定して下記式に従って算出した値である。The degree of densification of the acicular hematite particles was shown by S BET / S TEM as described above. Where S BET
Is the value of the specific surface area measured by the BET method.
S TEM is a value calculated according to the following equation, assuming that the particles are rectangular parallelepiped, using the average major axis diameter 1 cm and average minor axis diameter wcm of the particles measured from the electron micrograph.

【００８９】ＳTEM （ｍ2 ／ｇ）＝〔（４ｌｗ＋２
ｗ2 ）／（ｌｗ2 ・ρp ）〕×１０-4 （但し、ρp はヘマタイト粒子の真比重であり、５．２
ｇ／ｃｍ3 を用いた。） ＳTEM は、粒子内部及び粒子表面に脱水孔が全くなく表
面が平滑な粒子の比表面積であるから、ＳBET ／ＳTEM
の値が１に近いほど、ヘマタイト粒子の内部及び表面に
脱水孔が少なく表面が平滑な粒子、換言すれば、高密度
な粒子であることを意味する。S TEM (m 2 / g) = [(4lw + 2
w 2 ) / (lw 2 ρ p )] × 10 −4 (where ρ p is the true specific gravity of the hematite particles and is 5.2)
g / cm 3 was used. ) S TEM, since there is absolutely no surface dehydration holes inside the particles and the particle surface is a specific surface area of the smooth particles, S BET / S TEM
Is closer to 1, it means that the particles have less dewatered pores inside and on the surface of the hematite particles and have smoother surfaces, in other words, higher density particles.

【００９０】針状非磁性粒子の内部や表面に存在するＺ
ｒ、Ａｌ及びＳｉのそれぞれの量は蛍光Ｘ線分析により
測定した。Z existing inside or on the surface of the acicular nonmagnetic particles
The respective amounts of r, Al and Si were measured by X-ray fluorescence analysis.

【００９１】塗料粘度は、得られた塗料の２５℃におけ
る塗料粘度を、Ｅ型粘度計ＥＭＤ−Ｒ（株式会社東京計
器製）を用いて測定し、ずり速度Ｄ＝１．９２ｓｅｃ-1
における値で示した。The paint viscosity was measured at 25 ° C. using an E-type viscometer EMD-R (manufactured by Tokyo Keiki Co., Ltd.), and the shear rate D was 1.92 sec −1.
The values are indicated by

【００９２】樹脂吸着強度は、樹脂が粒子に吸着される
程度を示すものであり、下記の方法により求めた値が１
００に近い程、樹脂が針状非磁性粒子に強く吸着され、
良好であることを示す。The resin adsorption strength indicates the extent to which the resin is adsorbed on the particles, and the value obtained by the following method is 1
As the value is closer to 00, the resin is strongly adsorbed on the acicular nonmagnetic particles,
Indicates good.

【００９３】先ず、樹脂吸着量Ｗａを求める。粒子粉末
２０ｇとスルホン酸ナトリウム基を有する塩化ビニル−
酢酸ビニル共重合樹脂２ｇを溶解させた混合溶剤（メチ
ルエチルケトン２７．０ｇ、トルエン１６．２ｇ、シク
ロヘキサノン１０．８ｇ）５６ｇとを３ｍｍφスチール
ビーズ１２０ｇとともに１００ｍｌポリビンに入れ、６
０分間ペイントシェーカーで混合分散する。First, the resin adsorption amount Wa is determined. 20 g of particle powder and vinyl chloride having a sodium sulfonate group
56 g of a mixed solvent (27.0 g of methyl ethyl ketone, 16.2 g of toluene, 10.8 g of cyclohexanone) in which 2 g of a vinyl acetate copolymer resin was dissolved was put into a 100 ml polybin together with 120 g of 3 mmφ steel beads.
Mix and disperse with a paint shaker for 0 minutes.

【００９４】次に、この塗料組成物５０ｇを取り出し５
０ｍｌの沈降管に入れ回転数１００００ｒｐｍで１５分
間遠心分離を行い、固形部分と溶剤部分とを分離する。
そして、溶剤部分に含まれる樹脂固形分濃度を重量法に
よって定量し、仕込みの樹脂量との差し引きにより、固
形部分に存在する樹脂量を求め、これを粒子に対する樹
脂吸着量Ｗａ（ｍｇ／ｇ）とする。Next, 50 g of this coating composition was taken out and 5 g
The mixture is placed in a 0 ml settling tube and centrifuged at 10,000 rpm for 15 minutes to separate a solid portion and a solvent portion.
Then, the resin solid content concentration contained in the solvent portion is quantified by a gravimetric method, and the amount of the resin present in the solid portion is obtained by subtracting from the charged resin amount, and this is used as the resin adsorption amount Wa (mg / g) for the particles. And

【００９５】次に、先に分離した固形部分のみを１００
ｍｌトールビーカーに全量取り出し、これに混合溶剤
（メチルエチルケトン２５．０ｇ、トルエン１５．０
ｇ、シクロヘキサノン１０．０ｇ）５０ｇを加え、１５
分間超音波分散を行って懸濁状態にした後、５０ｍｌ沈
降管に入れ回転数１００００ｒｐｍで１５分間遠心分離
を行い、固形部分と溶剤部分とを分離する。そして、溶
剤部分の樹脂固形分濃度を測定することによって、粒子
表面に吸着していた樹脂のうち溶剤相に抽出された樹脂
量を定量する。Next, only the previously separated solid portion was
The whole amount was taken out into a 2 ml tall beaker, and mixed solvent (25.0 g of methyl ethyl ketone, 15.0 ml of toluene)
g, cyclohexanone 10.0 g) and 50 g.
The suspension is placed in a suspended state by ultrasonic dispersion for 5 minutes, and then placed in a 50 ml sedimentation tube and centrifuged at 10,000 rpm for 15 minutes to separate a solid portion and a solvent portion. Then, by measuring the resin solid content concentration in the solvent portion, the amount of resin extracted into the solvent phase among the resin adsorbed on the particle surface is quantified.

【００９６】さらに、上記固形部分のみの１００ｍｌト
ールビーカーへの全量取り出しから溶剤相に溶け出した
樹脂量の定量までの操作を２回繰り返し、合計３回の溶
剤相中における樹脂の抽出量の総和Ｗｅ（ｍｇ／ｇ）を
求め、下記の式に従って求めた値を樹脂吸着強度Ｔ
（％）とした。[0096] Further, the operation from the removal of the entire amount of only the solid portion into a 100 ml tall beaker to the determination of the amount of the resin dissolved in the solvent phase was repeated twice, and the total of the resin extraction amount in the solvent phase was repeated three times. We (mg / g) was determined, and the value determined according to the following equation was used as the resin adsorption strength T.
(%).

【００９７】Ｔ（％）＝〔（Ｗａ−Ｗｅ）／Ｗａ〕×１
００ Ｔが高いほど、ビヒクル中での粉体表面への樹脂吸着が
強固であり、良好であることを示す。T (%) = [(Wa-We) / Wa] × 1
The higher the 00T, the stronger and better the resin adsorption to the powder surface in the vehicle.

【００９８】非磁性下地層及び磁気記録層の塗膜表面の
光沢度は、「グロスメーターＵＧＶ−５Ｄ」（スガ試験
機株式会社製）を用いて塗膜の４５°光沢度を測定して
求めた。The glossiness of the coating surface of the non-magnetic underlayer and the magnetic recording layer was determined by measuring the 45 ° glossiness of the coating film using “Gloss Meter UGV-5D” (manufactured by Suga Test Instruments Co., Ltd.). Was.

【００９９】表面粗度Ｒａは、「Ｓｕｒｆｃｏｍ−５７
５Ａ」（東京精密株式会社製）を用いて塗布膜の中心線
平均粗さを測定した。The surface roughness Ra is calculated as follows: Surfcom-57
The center line average roughness of the coating film was measured using “5A” (manufactured by Tokyo Seimitsu Co., Ltd.).

【０１００】磁気記録媒体の耐久性については、下記の
走行耐久性とすり傷特性を求めることにより評価した。The durability of the magnetic recording medium was evaluated by obtaining the following running durability and scratch characteristics.

【０１０１】走行耐久性は、「Ｍｅｄｉａ Ｄｕｒａｂ
ｉｌｉｔｙ Ｔｅｓｔｅｒ ＭＤＴ−３０００」（Ｓｔ
ｅｉｎｂｅｒｇ Ａｓｓｏｃｉａｔｅｓ社製）を用い
て、負荷２００ｇｗ、ヘッドとテープとの相対速度１６
ｍ／ｓにおける実可動時間で評価した。実可動時間が長
い程走行耐久性が良いことを示す。The running durability was measured in “Media Durab”.
ility Tester MDT-3000 ”(St
einberg Associates), a load of 200 gw and a relative speed of 16 between the head and the tape.
Evaluation was made based on the actual operating time at m / s. The longer the actual operating time, the better the running durability.

【０１０２】すり傷特性は、走行後のテープの表面を顕
微鏡で観察し、すり傷の有無を目視で評価し、下記の４
段階の評価を行った。 Ａ：すり傷なし Ｂ：すり傷若干有り Ｃ：すり傷有り Ｄ：ひどいすり傷有りThe scratch characteristics were evaluated by observing the surface of the tape after running with a microscope and visually evaluating the presence or absence of scratches.
A rating was given on a scale. A: There is no scratch B: There is some scratch C: There is scratch D: There is severe scratch

【０１０３】塗膜強度は、「オートグラフ」（株式会社
島津製作所製）を用いて塗膜のヤング率を測定して求め
た。ヤング率は市販ビデオテープ「ＡＶ Ｔ−１２０
（日本ビクター株式会社製）」との相対値で表した。相
対値が高いほど良好であることを示す。The strength of the coating film was determined by measuring the Young's modulus of the coating film using “Autograph” (manufactured by Shimadzu Corporation). Young's modulus was measured using a commercially available video tape "AV T-120".
(Manufactured by Victor Company of Japan, Ltd.) ". The higher the relative value, the better.

【０１０４】磁気特性は、「振動試料型磁力計ＶＳＭ−
３Ｓ−１５」（東英工業株式会社製）を使用し、外部磁
場１０ＫＯｅまでかけて測定した。The magnetic characteristics are described in “Vibrating sample magnetometer VSM-
3S-15 "(manufactured by Toei Industry Co., Ltd.) using an external magnetic field of up to 10 KOe.

【０１０５】光透過の程度は、「自記光電分光光度計Ｕ
Ｖ−２１００」（株式会社島津製作所製）を用いて磁気
記録媒体について測定した光透過率の値を下記式に挿入
して算出した線吸収係数で示した。線吸収係数は、その
値が大きい程、光を透しにくいことを示す。The degree of light transmission is described in “Self-recording photoelectric spectrophotometer U
V-2100 "(manufactured by Shimadzu Corporation) was used to calculate the light transmittance of the magnetic recording medium, and the resulting value was inserted into the following equation to calculate the linear absorption coefficient. The larger the linear absorption coefficient is, the harder it is to transmit light.

【０１０６】尚、光透過率の値を測定するにあたって
は、上記磁気記録媒体に用いた非磁性支持体と同一の非
磁性支持体をブランクとして用いた。In measuring the light transmittance, the same non-magnetic support as the non-magnetic support used for the magnetic recording medium was used as a blank.

【０１０７】 線吸収係数（μｍ-1）＝〔ｌｎ（１／ｔ）〕／ＦＴ ｔ：λ＝９００ｎｍにおける光透過率（−） ＦＴ：測定に用いたフィルムの塗布層（非磁性下地層の
膜厚と磁気記録層の膜厚との総和）の厚み（μｍ）Linear absorption coefficient (μm −1 ) = [In (1 / t)] / FT t: Light transmittance at λ = 900 nm (−) FT: Coating layer of film used for measurement (nonmagnetic underlayer Thickness (μm) of the sum of the film thickness and the thickness of the magnetic recording layer)

【０１０８】磁気記録媒体を構成する非磁性支持体、非
磁性下地層及び磁気記録層の各層の厚みは、下記のよう
にして測定した。The thickness of each of the non-magnetic support, the non-magnetic underlayer, and the magnetic recording layer constituting the magnetic recording medium was measured as follows.

【０１０９】デジタル電子マイクロメーターＫ３５１Ｃ
（安立電気株式会社製）を用いて、先ず、非磁性支持体
の膜厚（Ａ）を測定する。次に、非磁性支持体と該非磁
性支持体上に形成された非磁性下地層との厚み（Ｂ）
（非磁性支持体の厚みと非磁性下地層の厚みとの総和）
を同様にして測定する。更に、非磁性下地層上に磁気記
録層を形成することにより得られた磁気記録媒体の厚み
（Ｃ）（非磁性支持体の厚みと非磁性下地層の厚みと磁
気記録層の厚みとの総和）を同様にして測定する。そし
て、非磁性下地層の厚みはＢ−Ａで示し、磁気記録層の
厚みはＣ−Ｂで示した。Digital electronic micrometer K351C
First, the film thickness (A) of the nonmagnetic support is measured using (manufactured by Anritsu Electric Co., Ltd.). Next, the thickness (B) of the nonmagnetic support and the nonmagnetic underlayer formed on the nonmagnetic support
(Sum of the thickness of the nonmagnetic support and the thickness of the nonmagnetic underlayer)
Is measured in the same manner. Further, the thickness (C) of the magnetic recording medium obtained by forming the magnetic recording layer on the nonmagnetic underlayer (the sum of the thickness of the nonmagnetic support, the thickness of the nonmagnetic underlayer, and the thickness of the magnetic recording layer) ) Is measured in the same manner. The thickness of the nonmagnetic underlayer is indicated by BA, and the thickness of the magnetic recording layer is indicated by CB.

【０１１０】＜紡錘状ゲータイト粒子粉末の製造＞硫酸
第一鉄水溶液とオキシ硫酸ジルコニウム水溶液と炭酸ナ
トリウム水溶液とを用いて、前記ゲータイト粒子の製造
法により得られたＺｒ換算で３．７８重量％のジルコ
ニウムを粒子内部に均一に含有している紡錘状ゲータイ
ト粒子粉末（平均長軸径０．１５０μｍ、平均短軸径
０．０１８３μｍ、軸比８．２、ＢＥＴ比表面積値１５
１．６ｍ2 ／ｇ及び幾何標準偏差値１．３６）１４４０
ｇを含む反応スラリーを得た。<Production of Spindle-Shaped Goethite Particle Powder> Using an aqueous solution of ferrous sulfate, an aqueous solution of zirconium oxysulfate, and an aqueous solution of sodium carbonate, 3.78% by weight of Zr obtained by the above-mentioned production method of goethite particles was converted. Spindle-shaped goethite particles containing zirconium uniformly inside the particles (average major axis diameter 0.150 μm, average minor axis diameter 0.0183 μm, axial ratio 8.2, BET specific surface area 15)
1.6 m 2 / g and geometric standard deviation 1.36) 1440
g was obtained as a reaction slurry.

【０１１１】これをプレスフィルターで濾過した後、純
水を用いて電気伝導度が３０μｓ以下になるまで水洗
し、次いで、乾燥、粉砕してジルコニウムを粒子内部に
均一に含有している紡錘状ゲータイト粒子粉末１３８０
ｇを得た。得られた紡錘状ゲータイト粒子粉末の樹脂吸
着強度は６５．３％であった。この紡錘状ゲータイト粒
子粉末を後述の非磁性下地層Ａの非磁性粒子粉末として
用いた。This was filtered with a press filter, washed with pure water until the electric conductivity became 30 μs or less, then dried and pulverized to obtain spindle-shaped goethite containing zirconium uniformly inside the particles. Particle powder 1380
g was obtained. The resin adsorption strength of the obtained spindle-shaped goethite particles was 65.3%. This spindle-shaped goethite particle powder was used as a nonmagnetic particle powder of a nonmagnetic underlayer A described later.

【０１１２】＜低密度紡錘状ヘマタイト粒子粉末の製造
＞上記紡錘状ゲータイト粒子粉末１２００ｇを水中に懸
濁させてスラリーとし、固形分濃度を８ｇ／ｌに調整し
た。このスラリー１５０ｌを加熱し、温度を６０℃と
し、０．１ＮのＮａＯＨ水溶液を加えてスラリーのｐＨ
値を９．０に調整した。<Production of Low Density Spindle-Shaped Hematite Particle Powder> 1200 g of the spindle-shaped goethite particle powder was suspended in water to form a slurry, and the solid concentration was adjusted to 8 g / l. The slurry was heated at 150 liters to a temperature of 60 ° C., and a 0.1N aqueous NaOH solution was added thereto to adjust the pH of the slurry.
The value was adjusted to 9.0.

【０１１３】次に、上記アルカリ性スラリー中に、焼結
防止剤として３号水ガラス３６．０ｇを徐々に加え、添
加が終わった後、６０分間熟成を行った。次に、このス
ラリーに０．１Ｎの酢酸溶液を加え、スラリーのｐＨ値
を６．０に調整した後、常法により、濾別、水洗、乾
燥、粉砕を行い、ケイ素の酸化物が粒子表面に被覆され
ている紡錘状ゲータイト粒子粉末１１６５ｇを得た。Ｓ
ｉＯ2 量は０．８３ｗｔ％であった。Next, 36.0 g of No. 3 water glass as a sintering inhibitor was gradually added to the alkaline slurry, and after the addition was completed, aging was performed for 60 minutes. Next, a 0.1N acetic acid solution was added to the slurry to adjust the pH value of the slurry to 6.0, followed by filtration, washing with water, drying, and pulverization by a conventional method. To obtain 1165 g of spindle-shaped goethite particles powder coated on the substrate. S
The iO 2 amount was 0.83 wt%.

【０１１４】得られた紡錘状ゲータイト粒子粉末のうち
１０００ｇを、ステンレス製回転炉に投入し、回転駆動
させながら空気中で３４０℃で６０分間熱処理を行って
脱水し、低密度紡錘状ヘマタイト粒子を得た。1000 g of the obtained spindle-shaped goethite particles was put into a stainless steel rotary furnace, and heat-treated at 340 ° C. for 60 minutes in the air while being driven to rotate to dehydrate, thereby obtaining low-density spindle-shaped hematite particles. Obtained.

【０１１５】次に、得られた低密度紡錘状ヘマタイト粒
子のうち１００ｇを純水１ｌにホモミキサー（特殊機化
工業株式会社製）を用いて解膠し、次いで、ヌッチェを
用いて濾別した後、純水を用いて電気伝導度が３０μｓ
以下になるまで水洗した。その後、乾燥、粉砕を行って
低密度紡錘状ヘマタイト粒子粉末９８ｇを得た。Next, 100 g of the obtained low-density spindle-shaped hematite particles were peptized in 1 l of pure water using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and then filtered off using Nutsche. Then, the electric conductivity is 30 μs using pure water.
It was washed with water until it became the following. Thereafter, drying and pulverization were performed to obtain 98 g of low-density spindle-shaped hematite particle powder.

【０１１６】得られたジルコニウムを含有している低密
度紡錘状ヘマタイト粒子は、平均長軸径０．１１６μ
ｍ、平均短軸径０．０１５３μｍ、軸比７．６、ＢＥＴ
比表面積値（ＳBET ）１８７．６ｍ2 ／ｇ、密度化の程
度ＳBET ／ＳTEM は３．５０、Ｚｒ含有量は４．１５重
量％及び幾何標準偏差値１．３６であった。樹脂吸着強
度は６８．８％であった。この低密度紡錘状ヘマタイト
粒子粉末を、後述の非磁性下地層Ｂの非磁性粒子粉末と
して用いた。The obtained low-density spindle-shaped hematite particles containing zirconium had an average major axis diameter of 0.116 μm.
m, average minor axis diameter 0.0153 μm, axial ratio 7.6, BET
The specific surface area (S BET ) was 187.6 m 2 / g, the degree of densification S BET / S TEM was 3.50, the Zr content was 4.15% by weight, and the geometric standard deviation value was 1.36. The resin adsorption strength was 68.8%. This low-density spindle-shaped hematite particle powder was used as a nonmagnetic particle powder of a nonmagnetic underlayer B described later.

【０１１７】＜高密度紡錘状ヘマタイト粒子粉末の製造
＞上記低密度紡錘状ヘマタイト粒子粉末８５０ｇをセラ
ミック製の回転炉に投入し、回転駆動させながら空気中
６７０℃で２５分間熱処理を行い、脱水孔の封孔処理を
行った。<Production of High-Density Spindle-Shaped Hematite Particle Powder> 850 g of the above-mentioned low-density spindle-shaped hematite particle powder was put into a ceramic rotary furnace, and heat-treated at 670 ° C. for 25 minutes in air while being driven to rotate. Was carried out.

【０１１８】得られた高密度化された紡錘状ヘマタイト
粒子粉末１００ｇを純水１ｌにホモミキサー（特殊機化
工業株式会社製）を用いて解膠し、次いで、ヌッチェを
用いて濾別した後、純水を用いて電気伝導度が３０μｓ
以下になるまで水洗した。その後、乾燥、粉砕を行って
高密度紡錘状ヘマタイト粒子粉末９８ｇを得た。100 g of the obtained densified spindle-shaped hematite particles was peptized in 1 liter of pure water by using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and then filtered by Nutsche. 30μs electric conductivity using pure water
It was washed with water until it became the following. Thereafter, drying and pulverization were performed to obtain 98 g of high-density spindle-shaped hematite particle powder.

【０１１９】高密度紡錘状ヘマタイト粒子粉末は、平均
長軸径が０．１１５μｍ、平均短軸径が０．０１５５μ
ｍ、軸比が７．４、ＢＥＴ比表面積値（ＳBET ）が６
０．３ｍ2 ／ｇ、密度化の程度ＳBET ／ＳTEM が１．１
４及び幾何標準偏差値が１．３６であった。Ｚｒ含有量
は４．１５重量％であった。また、樹脂吸着強度は７
３．８％であった。この高密度紡錘状ヘマタイト粒子粉
末を、後述の非磁性下地層Ｃの非磁性粒子粉末として用
いた。The high-density spindle-shaped hematite particles have an average major axis diameter of 0.115 μm and an average minor axis diameter of 0.0155 μm.
m, axial ratio 7.4, BET specific surface area value (S BET ) 6
0.3 m 2 / g, degree of density increase S BET / S TEM is 1.1
4 and the geometric standard deviation value were 1.36. The Zr content was 4.15% by weight. The resin adsorption strength is 7
3.8%. This high-density spindle-shaped hematite particle powder was used as a non-magnetic particle powder of a non-magnetic underlayer C described later.

【０１２０】＜非磁性下地層の製造＞上記で得られた紡
錘状ゲータイト粒子粉末、低密度紡錘状ヘマタイト粒子
粉末及び高密度紡錘状ヘマタイト粒子粉末を用い、各粒
子粉末１２ｇと結合剤樹脂溶液（スルホン酸ナトリウム
基を有する塩化ビニル−酢酸ビニル共重合樹脂３０重量
％とシクロヘキサノン７０重量％）及びシクロヘキサノ
ンとを混合して混合物（固形分率７２％）を得、この混
合物を更にプラストミルで３０分間混練して３種類の混
練物を得た。<Production of Nonmagnetic Underlayer> Using the spindle-shaped goethite particle powder, low-density spindle-shaped hematite particle powder, and high-density spindle-shaped hematite particle powder obtained above, 12 g of each particle powder and a binder resin solution ( A mixture (30% by weight of vinyl chloride-vinyl acetate copolymer resin having sodium sulfonate group and 70% by weight of cyclohexanone) and cyclohexanone are mixed to obtain a mixture (solid content: 72%), and this mixture is further kneaded with a plastmill for 30 minutes. Thus, three kinds of kneaded materials were obtained.

【０１２１】この３種類の混練物をそれぞれ１４０ｍｌ
ガラス瓶に１．５ｍｍφガラスビーズ９５ｇ、結合剤樹
脂溶液（スルホン酸ナトリウム基を有するポリウレタン
樹脂３０重量％、溶剤（メチルエチルケトン：トルエン
＝１：１）７０重量％）、シクロヘキサノン、メチルエ
チルケトン及びトルエンとともに添加し、ペイントシェ
ーカーで６時間混合・分散を行って３種類の塗料組成物
を得た。Each of these three types of kneaded materials was 140 ml
95 g of 1.5 mmφ glass beads, a binder resin solution (30% by weight of a polyurethane resin having a sodium sulfonate group, 70% by weight of a solvent (methyl ethyl ketone: toluene = 1: 1) 70% by weight), cyclohexanone, methyl ethyl ketone and toluene are added to a glass bottle; Mixing and dispersion were performed for 6 hours using a paint shaker to obtain three types of coating compositions.

【０１２２】得られた紡錘状ゲータイト粒子粉末、低密
度紡錘状ヘマタイト粒子粉末及び高密度紡錘状ヘマタイ
ト粒子粉末のそれぞれを含む塗料の組成は、下記の通り
であった。The compositions of the coatings containing the obtained spindle-shaped goethite particles, low-density spindle-shaped hematite particles, and high-density spindle-shaped hematite particles were as follows.

【０１２３】紡錘状ゲータイト粒子粉末、低密度紡錘状
ヘマタイト粒子粉末又は高密度紡錘 状ヘマタイト粒子粉末 １００重量部 スルホン酸ナトリウム基を有する 塩化ビニル−酢酸ビニル共重合樹脂 １０重量部 スルホン酸ナトリウム基を有するポリウレタン樹脂 １０重量部 シクロヘキサノン ４４．６重量部 メチルエチルケトン １１１．４重量部 トルエン ６６．９重量部Spindle-shaped goethite particle powder, low-density spindle-shaped hematite particle powder or high-density spindle-shaped hematite particle powder 100 parts by weight Vinyl chloride-vinyl acetate copolymer resin having sodium sulfonate group 10 parts by weight Sodium sulfonate group Polyurethane resin 10 parts by weight Cyclohexanone 44.6 parts by weight Methyl ethyl ketone 111.4 parts by weight Toluene 66.9 parts by weight

【０１２４】得られた３種類の塗料をそれぞれ厚さ１２
μｍのポリエチレンテレフタレートフィルム上にアプリ
ケーターを用いて５５μｍの厚さに塗布し、次いで、乾
燥させることにより３種類の非磁性下地層を形成した。
非磁性下地層Ａの厚みは３．６μｍであった。非磁性下
地層Ｂの厚みは３．５μｍ、非磁性下地層Ｃの厚みは
３．３μｍであった。Each of the three types of paints was applied to a thickness of 12
It was applied to a thickness of 55 μm on a polyethylene terephthalate film having a thickness of 55 μm using an applicator, and then dried to form three types of nonmagnetic underlayers.
The thickness of the nonmagnetic underlayer A was 3.6 μm. The thickness of the nonmagnetic underlayer B was 3.5 μm, and the thickness of the nonmagnetic underlayer C was 3.3 μm.

【０１２５】非磁性粒子粉末として紡錘状ゲータイト粒
子粉末を用いて得られた非磁性下地層Ａは、光沢が１８
１％、表面粗度Ｒａが１１．６ｎｍであり、基体のヤン
グ率（相対値）は１３３であった。The nonmagnetic underlayer A obtained by using the spindle-shaped goethite particle powder as the nonmagnetic particle powder has a gloss of 18%.
The surface roughness Ra was 11.6 nm, and the Young's modulus (relative value) of the substrate was 133.

【０１２６】非磁性粒子粉末として低密度紡錘状ヘマタ
イト粒子粉末を用いて得られた非磁性下地層Ｂは、光沢
が１９０％、表面粗度Ｒａが１０．２ｎｍであり、基体
のヤング率（相対値）は１３３であった。The non-magnetic underlayer B obtained by using low-density spindle-shaped hematite particle powder as the non-magnetic particle powder has a gloss of 190%, a surface roughness Ra of 10.2 nm, and a Young's modulus (relative Value) was 133.

【０１２７】非磁性粒子粉末として高密度紡錘状ヘマタ
イト粒子粉末を用いて得られた非磁性下地層Ｃは、光沢
が２０６％、表面粗度Ｒａが６．９ｎｍであり、基体の
ヤング率（相対値）は１３５であった。The non-magnetic underlayer C obtained by using the high-density spindle-shaped hematite particle powder as the non-magnetic particle powder has a gloss of 206%, a surface roughness Ra of 6.9 nm, and a Young's modulus (relative Value) was 135.

【０１２８】＜磁気記録層の製造＞鉄を主成分とする紡
錘状金属磁性粒子粉末（平均長軸径０．１５３μｍ、平
均短軸径０．０１９１μｍ、軸比８．０１、保磁力１７
１０Ｏｅ、飽和磁化値１２５．３ｅｍｕ／ｇ、幾何標準
偏差１．３５）１２ｇ、研磨剤（商品名：ＡＫＰ−３
０、住友化学（株）製）１．２ｇ、カーボンブラック
（商品名：＃３２５０Ｂ、三菱化成（株）製）０．３６
ｇ、結合剤樹脂溶液（スルホン酸ナトリウム基を有する
塩化ビニル−酢酸ビニル共重合樹脂３０重量％とシクロ
ヘキサノン７０重量％）及びシクロヘキサノンとを混合
して混合物（固形分率７８％）を得、この混合物を更に
プラストミルで３０分間混練して混練物を得た。<Production of Magnetic Recording Layer> Spindle-shaped metal magnetic particles containing iron as a main component (average major axis diameter 0.153 μm, average minor axis diameter 0.0191 μm, axial ratio 8.01, coercive force 17)
10 Oe, 12 g of saturation magnetization value 125.3 emu / g, geometric standard deviation 1.35), 12 g of abrasive (trade name: AKP-3)
0, manufactured by Sumitomo Chemical Co., Ltd.) 1.2 g, carbon black (trade name: # 3250B, manufactured by Mitsubishi Kasei Co., Ltd.) 0.36
g, a binder resin solution (vinyl chloride-vinyl acetate copolymer resin having sodium sulfonate group 30% by weight and cyclohexanone 70% by weight) and cyclohexanone were mixed to obtain a mixture (solid content 78%). Was further kneaded with a plast mill for 30 minutes to obtain a kneaded material.

【０１２９】この混練物を１４０ｍｌガラス瓶に１．５
ｍｍφガラスビーズ９５ｇ、結合剤樹脂溶液（スルホン
酸ナトリウム基を有するポリウレタン樹脂３０重量％、
溶剤（メチルエチルケトン：トルエン＝１：１）７０重
量％）、シクロヘキサノン、メチルエチルケトン及びト
ルエンとともに添加し、ペイントシェーカーで６時間混
合・分散を行って磁性塗料を得た。更に、潤滑剤及び硬
化剤を加えた後、ペイントシェーカーで１５分間混合・
分散した。This kneaded material was placed in a 140 ml glass bottle for 1.5 times.
glass beads 95 g, binder resin solution (polyurethane resin having sodium sulfonate group 30% by weight,
A solvent (methyl ethyl ketone: toluene = 1: 1) 70% by weight), cyclohexanone, methyl ethyl ketone and toluene were added, and the mixture was mixed and dispersed with a paint shaker for 6 hours to obtain a magnetic paint. After adding the lubricant and hardener, mix with a paint shaker for 15 minutes.
Dispersed.

【０１３０】得られた磁性塗料の組成は下記の通りであ
った。 鉄を主成分とする紡錘状金属磁性粒子粉末 １００重量部 スルホン酸ナトリウム基を有する 塩化ビニル−酢酸ビニル共重合樹脂 １０重量部 スルホン酸ナトリウム基を有するポリウレタン樹脂 １０重量部 研磨剤（ＡＫＰ−３０） １０重量部 カーボンブラック（＃３２５０Ｂ） ３．０重量部 潤滑剤（ミリスチン酸：ステアリン酸ブチル＝１：２） ３．０重量部 硬化剤（ポリイソシアネート） ５．０重量部 シクロヘキサノン ６５．８重量部 メチルエチルケトン １６４．５重量部 トルエン ９８．７重量部The composition of the obtained magnetic paint was as follows. Spindle-shaped magnetic metal particles containing iron as a main component 100 parts by weight Vinyl chloride-vinyl acetate copolymer resin having sodium sulfonate group 10 parts by weight Polyurethane resin having sodium sulfonate group 10 parts by weight Abrasive (AKP-30) 10 parts by weight Carbon black (# 3250B) 3.0 parts by weight Lubricant (myristic acid: butyl stearate = 1: 2) 3.0 parts by weight Hardener (polyisocyanate) 5.0 parts by weight Cyclohexanone 65.8 parts by weight Methyl ethyl ketone 164.5 parts by weight Toluene 98.7 parts by weight

【０１３１】得られた磁性塗料を前記非磁性下地層Ａ、
Ｂ及びＣのそれぞれの上にアプリケーターを用いて１５
μｍの厚さに塗布した後、磁場中において配向・乾燥
し、次いで、カレンダー処理を行った後、６０℃で２４
時間硬化反応を行い０．５インチ幅にスリットして磁気
テープを得た。磁気記録層の厚みはいずれも１．１μｍ
であった。The obtained magnetic paint was coated with the non-magnetic underlayer A,
15 with an applicator on each of B and C
After coating to a thickness of μm, orienting and drying in a magnetic field, and then performing a calendering process,
A time-curing reaction was performed, and a 0.5-inch width slit was obtained to obtain a magnetic tape. The thickness of each magnetic recording layer is 1.1 μm.
Met.

【０１３２】非磁性下地層Ａの上に磁気記録層を形成さ
せて得られた磁気テープは、Ｈｃが１７７１Ｏｅ、角型
比（Ｂｒ／Ｂｍ）が０．８７、光沢度が１９５％、表面
粗度Ｒａが１０．２ｎｍ、ヤング率（相対値）が１３
６、線吸収係数が１．２３、走行耐久性が２１．２分、
すり傷特性がＢであった。A magnetic tape obtained by forming a magnetic recording layer on the non-magnetic underlayer A had an Hc of 1771 Oe, a squareness ratio (Br / Bm) of 0.87, a gloss of 195%, and a surface roughness of 175%. Degree Ra is 10.2 nm, Young's modulus (relative value) is 13
6, the line absorption coefficient is 1.23, the running durability is 21.2 minutes,
The scratch characteristics were B.

【０１３３】非磁性下地層Ｂの上に磁気記録層を形成さ
せて得られた磁気テープは、Ｈｃが１７７３Ｏｅ、角型
比（Ｂｒ／Ｂｍ）が０．８７、光沢度が２００％、表面
粗度Ｒａが８．８ｎｍ、ヤング率（相対値）が１３７、
線吸収係数が１．２３、走行耐久性が２４．６分、すり
傷特性がＡであった。The magnetic tape obtained by forming a magnetic recording layer on the non-magnetic underlayer B has a Hc of 1773 Oe, a squareness ratio (Br / Bm) of 0.87, a gloss of 200%, and a surface roughness of Degree Ra is 8.8 nm, Young's modulus (relative value) is 137,
The linear absorption coefficient was 1.23, the running durability was 24.6 minutes, and the scratch characteristics were A.

【０１３４】非磁性下地層Ｃの上に磁気記録層を形成さ
せて得られた磁気テープは、Ｈｃが１７８０Ｏｅ、角型
比（Ｂｒ／Ｂｍ）が０．８９、光沢度が２１６％、表面
粗度Ｒａが７．０ｎｍ、ヤング率（相対値）が１３７、
線吸収係数が１．２３、走行耐久性が２７．６分、すり
傷特性がＡであった。A magnetic tape obtained by forming a magnetic recording layer on the non-magnetic underlayer C has an Hc of 1780 Oe, a squareness ratio (Br / Bm) of 0.89, a glossiness of 216%, and a surface roughness of The degree Ra is 7.0 nm, the Young's modulus (relative value) is 137,
The linear absorption coefficient was 1.23, the running durability was 27.6 minutes, and the scratch characteristics were A.

【０１３５】[0135]

【作用】本発明において最も重要な点は、Ｚｒ換算で
０．０５〜３０重量％のジルコニウムを粒子内部に含有
している非磁性粒子粉末、必要により、さらに、アルミ
ニウムの水酸化物、アルミニウムの酸化物、ケイ素の水
酸化物及びケイ素の酸化物の少なくとも１種で粒子表面
が被覆されている鉄を主成分とする針状非磁性粒子粉末
を非磁性下地層用の非磁性粒子粉末として用いた場合に
は、非磁性下地層の表面平滑性と基体の強度を向上させ
ることができ、当該非磁性下地層の上に磁気記録層を設
けた場合に、磁気記録層の光透過率を小さくし、表面平
滑で、強度が大きく、且つ、耐久性に優れている磁気記
録媒体を得ることができるという事実である。The most important point in the present invention is that the non-magnetic particle powder contains 0.05 to 30% by weight of zirconium in terms of Zr in the inside of the particle, and if necessary, further contains aluminum hydroxide and aluminum. Needle-shaped nonmagnetic particle powder mainly composed of iron, whose particle surface is coated with at least one of oxide, silicon hydroxide and silicon oxide, as nonmagnetic particle powder for a nonmagnetic underlayer. In this case, the surface smoothness of the nonmagnetic underlayer and the strength of the substrate can be improved, and when the magnetic recording layer is provided on the nonmagnetic underlayer, the light transmittance of the magnetic recording layer is reduced. However, it is a fact that a magnetic recording medium having a smooth surface, high strength, and excellent durability can be obtained.

【０１３６】非磁性下地層の表面平滑性と基体の強度及
び磁気記録媒体の耐久性をより向上させることができた
理由について、本発明者は、非磁性粒子のビヒクル中に
おける結合剤樹脂との樹脂吸着強度が高まり、その結
果、非磁性下地層中における非磁性粒子と樹脂との密着
度や非磁性下地層自体の非磁性支持体への密着度が高ま
ったことによるものと考えている。Regarding the reason why the surface smoothness of the non-magnetic underlayer, the strength of the substrate, and the durability of the magnetic recording medium were able to be further improved, the present inventor considered that the non-magnetic particles were mixed with the binder resin in the vehicle. It is considered that the resin adsorption strength was increased, and as a result, the adhesion between the nonmagnetic particles and the resin in the nonmagnetic underlayer and the adhesion of the nonmagnetic underlayer itself to the nonmagnetic support were increased.

【０１３７】[0137]

【実施例】次に、実施例並びに比較例を挙げる。Next, examples and comparative examples will be described.

【０１３８】＜針状ゲータイト粒子粉末の種類＞ 非磁性粒子Ａ１、Ａ８ 針状ゲータイト粒子粉末の平均長軸径、平均短軸径、幾
何標準偏差値、軸比及びＢＥＴ比表面積、ジルコニウム
含有の有無及び量、表面被覆物の有無並びに樹脂吸着強
度等が相違する針状ゲータイト粒子粉末２種類を準備し
た。<Types of Acicular Goethite Particle Powder> Non-magnetic Particles A1, A8 Average major axis diameter, average minor axis diameter, geometric standard deviation value, axial ratio and BET specific surface area of acicular goethite particle powder, presence or absence of zirconium And two types of acicular goethite particle powders having different amounts and amounts, the presence or absence of a surface coating, and the resin adsorption strength were prepared.

【０１３９】針状ゲータイト粒子粉末Ａ１及びＡ８の主
要製造条件を表１に、諸特性を表２に示す。Table 1 shows the main production conditions of the acicular goethite particle powders A1 and A8, and Table 2 shows various properties.

【０１４０】＜針状ヘマタイト粒子粉末の種類＞ 非磁性粒子Ａ２〜Ａ７、Ａ９〜Ａ１１ 出発原料である針状ゲータイト粒子粉末の基本生成反
応、焼結防止剤の種類及び量、平均長軸径、平均短軸
径、幾何標準偏差値、軸比、比表面積及び密度化の程
度、ジルコニウム含有の有無及び量、表面被覆物の有
無、種類及び量並びに樹脂吸着強度が種々相違する針状
ヘマタイト粒子粉末を準備した。尚、ジルコニウムを含
有している針状ヘマタイト粒子は、いずれも粒子内部に
ジルコニウムを均一に含有している粒子である。<Types of Acicular Hematite Particle Powder> Non-magnetic particles A2 to A7, A9 to A11 Basic formation reaction of acicular goethite particle powder as a starting material, type and amount of sintering inhibitor, average major axis diameter, Acicular hematite particle powders with various differences in average minor axis diameter, geometric standard deviation value, axial ratio, specific surface area and degree of densification, presence or absence and amount of zirconium, presence or absence, type and amount of surface coating, and resin adsorption strength Was prepared. Incidentally, the acicular hematite particles containing zirconium are all particles containing zirconium uniformly inside the particles.

【０１４１】針状ヘマタイト粒子Ａ２〜Ａ７、Ａ９〜Ａ
１１の主要製造条件を表１に、諸特性を表２に示す。Acicular hematite particles A2 to A7, A9 to A
Table 1 shows the main manufacturing conditions of No. 11 and Table 2 shows various characteristics.

【０１４２】[0142]

【表１】 [Table 1]

【０１４３】[0143]

【表２】 [Table 2]

【０１４４】尚、針状非磁性粒子の表面被覆処理は、非
磁性粒子の種類、被覆物の種類及び量を種々変化させた
以外は、下記の方法によった。Incidentally, the surface coating treatment of the acicular non-magnetic particles was carried out by the following method, except that the type of the non-magnetic particles and the type and amount of the coating were variously changed.

【０１４５】非磁性粒子Ａ４を含む濃度が９９ｇ／ｌの
スラリー５ｌを加熱して６０℃とし、このスラリー中に
１．０ＮのＮａＡｌＯ2 溶液１５５．８ｍｌ（針状ヘマ
タイト粒子に対しＡｌ換算で０．８５重量％に相当す
る。）を加え、３０分間保持した後、酢酸を用いてｐＨ
値を７．５に調整した。次いで、前記発明の実施の形態
と同様にして濾別、水洗、乾燥した後、粉砕して粒子表
面が被覆物により被覆されている針状ヘマタイト粒子粉
末を得た。5 l of a slurry containing the non-magnetic particles A4 and having a concentration of 99 g / l were heated to 60 ° C., and 155.8 ml of a 1.0 N NaAlO 2 solution was added to the slurry (05.8 in terms of Al with respect to acicular hematite particles). .85% by weight), and after holding for 30 minutes, the pH was adjusted using acetic acid.
The value was adjusted to 7.5. Next, after filtering, washing with water and drying in the same manner as in the embodiment of the present invention, the powder was pulverized to obtain acicular hematite particle powder having a particle surface covered with a coating.

【０１４６】＜非磁性下地層の製造＞ 実施例１〜７及び比較例１〜４ 非磁性粒子Ａ１〜Ａ１１の針状非磁性粒子粉末を用いて
前記発明の実施の形態と同様にして非磁性下地層を得
た。<Production of Non-Magnetic Underlayer> Examples 1 to 7 and Comparative Examples 1 to 4 Non-magnetic layers were prepared in the same manner as in the embodiment of the present invention using the acicular non-magnetic particles of the non-magnetic particles A1 to A11. An underlayer was obtained.

【０１４７】この時の主要製造条件及び諸特性を表３に
示す。Table 3 shows the main manufacturing conditions and various characteristics at this time.

【０１４８】[0148]

【表３】 [Table 3]

【０１４９】＜磁気記録媒体の製造＞ 実施例８〜２４及び比較例５〜１２ 非磁性下地層の種類、磁性粒子粉末の種類を種々変化さ
せた以外は、前記発明の実施の形態と同様にして磁気記
録媒体を製造した。<Manufacture of Magnetic Recording Medium> Examples 8 to 24 and Comparative Examples 5 to 12 Except that the type of the non-magnetic underlayer and the type of the magnetic particle powder were variously changed, the same as in the above-described embodiment of the present invention. Thus, a magnetic recording medium was manufactured.

【０１５０】この時の主要製造条件及び諸特性を表４及
び表５に示す。Tables 4 and 5 show the main production conditions and various characteristics at this time.

【０１５１】[0151]

【表４】 [Table 4]

【０１５２】[0152]

【表５】 [Table 5]

【０１５３】[0153]

【発明の効果】本発明に係る磁気記録媒体は、粒子内部
にジルコニウムをほぼ均一に含有している非磁性粒子粉
末であることに起因して、基体としての強度と表面性に
優れている非磁性下地層を得ることができ、該非磁性下
地層を用いて磁気記録媒体とした場合において光透過率
が小さく、表面平滑で、強度が大きい磁気記録媒体を得
ることができ、しかも、該磁気記録媒体は、非磁性下地
層用非磁性粒子粉末として粒子内部にジルコニウムを均
一に含有している針状非磁性粒子粉末を用いたことに起
因して耐久性に優れたものであるので、高密度記録用磁
気記録媒体として好ましいものである。The magnetic recording medium according to the present invention is a non-magnetic particle powder which contains zirconium almost uniformly in the inside of the particle, and has excellent strength and surface properties as a substrate. A magnetic underlayer can be obtained, and when a magnetic recording medium is formed using the nonmagnetic underlayer, a magnetic recording medium having a small light transmittance, a smooth surface, and a high strength can be obtained. The medium has excellent durability due to the use of acicular non-magnetic particles containing zirconium uniformly inside the particles as the non-magnetic particles for the non-magnetic underlayer. It is preferable as a magnetic recording medium for recording.

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】 非磁性支持体と該非磁性支持体上に形成
される非磁性粒子粉末と結合剤樹脂とを含む非磁性下地
層とからなる磁気記録媒体用基体において、前記非磁性
粒子粉末はＺｒ換算で０．０５〜３０重量％のジルコニ
ウムを粒子内部に含有している鉄を主成分とする針状非
磁性粒子粉末であることを特徴とする非磁性下地層を有
する磁気記録媒体用基体。1. A magnetic recording medium substrate comprising a non-magnetic support and a non-magnetic underlayer containing a binder resin and a non-magnetic particle powder formed on the non-magnetic support, wherein the non-magnetic particle powder is A substrate for a magnetic recording medium having a non-magnetic underlayer, characterized in that it is an acicular non-magnetic particle powder containing iron as a main component and containing 0.05 to 30% by weight of zirconium in terms of Zr. . 【請求項２】 非磁性支持体と該非磁性支持体上に形成
される非磁性粒子粉末と結合剤樹脂とを含む非磁性下地
層とからなる磁気記録媒体用基体において、前記非磁性
粒子粉末はＺｒ換算で０．０５〜３０重量％のジルコニ
ウムを粒子内部に含有するとともに、アルミニウムの水
酸化物、アルミニウムの酸化物、ケイ素の水酸化物及び
ケイ素の酸化物の少なくとも１種で粒子表面が被覆され
ている鉄を主成分とする針状非磁性粒子粉末からなるこ
とを特徴とする非磁性下地層を有する磁気記録媒体用基
体。2. A magnetic recording medium substrate comprising a non-magnetic support and a non-magnetic underlayer containing a non-magnetic particle powder formed on the non-magnetic support and a binder resin, wherein the non-magnetic particle powder is The particle surface contains 0.05 to 30% by weight of zirconium in terms of Zr, and the particle surface is coated with at least one of aluminum hydroxide, aluminum oxide, silicon hydroxide and silicon oxide. A magnetic recording medium substrate having a non-magnetic underlayer, characterized in that the substrate comprises a needle-like non-magnetic particle powder containing iron as a main component. 【請求項３】 請求項１又は請求項２記載の非磁性下地
層を有する磁気記録媒体用基体の上に、磁性粒子粉末と
結合剤樹脂とを含む磁気記録層を設けた磁気記録媒体。3. A magnetic recording medium comprising a magnetic recording medium having a non-magnetic underlayer according to claim 1 and a magnetic recording layer containing magnetic particle powder and a binder resin on the substrate.
JP34383497A 1997-11-28 1997-11-28 Magnetic recording medium substrate having non-magnetic underlayer and magnetic recording medium using the substrate Expired - Fee Related JP3661738B2 (en)

Priority Applications (3)

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JP34383497A JP3661738B2 (en) 1997-11-28 1997-11-28 Magnetic recording medium substrate having non-magnetic underlayer and magnetic recording medium using the substrate
US09/198,390 US6159592A (en) 1997-11-28 1998-11-24 Magnetic recording medium
EP98309710A EP0923068A3 (en) 1997-11-28 1998-11-26 Magnetic recording medium

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JP3661738B2 JP3661738B2 (en) 2005-06-22

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018074598A1 (en) * 2016-10-21 2018-04-26 国立大学法人 岡山大学 Iron oxide for red pigments and method for producing same
WO2019123670A1 (en) * 2017-12-20 2019-06-27 国立大学法人 岡山大学 Iron oxide for orange pigment and method for producing same

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018074598A1 (en) * 2016-10-21 2018-04-26 国立大学法人 岡山大学 Iron oxide for red pigments and method for producing same
WO2019123670A1 (en) * 2017-12-20 2019-06-27 国立大学法人 岡山大学 Iron oxide for orange pigment and method for producing same
JPWO2019123670A1 (en) * 2017-12-20 2020-12-10 国立大学法人 岡山大学 Iron oxide for orange pigments and its manufacturing method

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